BOGOTA, COLOMBIA, JUNE 27 -- Despite the $40 million or so that the Reagan administration spends each year in South America to stanch cocaine production, Colombia's drug mafia continues to earn an illicit couple of billion dollars or more.

For every acre of hardy coca bushes destroyed in Peru or Bolivia, several new ones have sprouted.

For every ton of cocaine or its equivalent in unrefined coca paste seized in the principal narcotics-producing states, more than five tons of cocaine are believed to have been shipped to the United States.

For all its steps forward, in short, the Reagan administration's war on cocaine is still losing ground, which raises questions about the campaign's weapons, financing and chosen battlefield.

The gap between the Reagan administration's goals and the sad shortcomings of its South American antinarcotics campaign emerged starkly in interviews this month in Colombia, Bolivia and Peru.

Despite added funding for law enforcement, coca eradication and economic development, and despite strengthened political commitments from Andean country leaders to fight narcotics, cocaine remains the most dynamic growth industry in this afflicted region, spilling across borders and employing ever larger numbers of people.

That paradox haunts the anticocaine war.

Officially, the Reagan administration takes the sanguine view that antidrug efforts are still building and will eventually become a match for the traffickers. "We are still on the beach, but mobilizing," said this year's State Department report on narcotics.

But the prevailing view among many on the front lines here is that current formulas for cutting cocaine's supply lines are simply not going to work.

"No one really believes these programs will make much of a difference," said a U.S. diplomat in a South American capital, echoing comments by other officials, law enforcement agents and development workers in the area.

The drug-fighting alliance between the world's northern cocaine consumers and South America's hard-pressed producers is an uneasy one. Neither side entirely trusts the other's commitment.

South American officials often complain that U.S. and European assistance remains depressingly inadequate for a war that the continent's debt-ridden, export-poor nations cannot fund themselves.

If the narcotics business is to be excised, South American governments say they need to be able to offer economic alternatives to their populations. As murderous and corrupting as cocaine has become for them, its tainted profits also have kept some Andean economies from outright collapse.

South Americans also argue that local efforts to eliminate cocaine are bound to be futile unless more is done to choke U.S. demand for the drug. The number of cocaine users in the United States has remained stable at about 12 million people since the late 1970s, and the frequency of use by individual consumers has increased, according to surveys by the National Institute of Drug Abuse.

U.S. officials say the region's antidrug drive is frequently stymied by intimidated or corrupt authorities and by the higher priorities that local governments frequently give to fighting guerrillas or managing other crises.Aerial and ground surveys indicate that cultivation of coca leaves -- cocaine's raw source -- is increasing at least 5 to 10 percent a year in Peru and Bolivia despite U.S.-supported eradication efforts in these main coca-growing states.

Cocaine consumption in the United States swelled from 34 tons in 1982 to 79 tons in 1985, according to U.S. government estimates. No firm estimate exists for current levels, but some officials cite figures exceeding 100 tons. The steady rise in supply has cut cocaine's street prices to as much as half of what they were three years ago in some parts of the country. Europe, too, is receiving increased quantities of the smuggled drug.

About 75 percent of the cocaine boom is controlled by a violent mafia -- the "Medellin cartel," named after the Colombian city where its headquarters are located. Law enforcement officers lost their main weapon against the drug syndicate this week when Colombia's Supreme Court effectively blocked the extradition to the United States of any more Colombian nationals. The court declared unconstitutional a law here that had ratified the U.S.-Colombian extradition treaty signed in 1979.

Meanwhile, traffickers have entered alliances of convenience with leftist guerrillas, becoming an even more formidable threat to regional security.

In Colombian jungles, Marxist rebels levy taxes on coca cultivation and stand guard over cocaine processing facilities; the drug money they earn buys arms. In Peru, Maoist insurgents have swarmed into the coca-rich Upper Huallaga Valley to share in drug profits. Authorities blame recent killings there of antinarcotics police on a branch of the Shining Path guerrilla movement. In Bolivia, which has no guerrillas, government officials accuse drug dealers of financing peasant rebellions against a proposed coca eradication plan.

Perhaps most alarming of all, the cocaine business has spread into South American nations once little affected by it. Coca plantations and chemical laboratories have sprung up in remote parts of Ecuador and Brazil. Transshipment points for moving cocaine from wilderness labs to the mean streets and posh residences of the United States and Europe now span the continent, from Venezuela to Argentina. Ironically, the inefficacy of existing cocaine-elimination schemes has become more apparent as South American governments have undertaken concerted action against the drug business.

Colombia moved first, enraged by the cold-blooded, mafia-ordered murder in 1984 of justice minister Rodrigo Lara Bonilla. Since then, numerous drug killings of judges, journalists, policemen and others have fortified the government's resolve despite setbacks.

Peruvian President Alan Garcia joined the drive in earnest shortly after taking office in 1985, launching a series of raids on cocaine processing facilities that have expanded in force and territory.

Bolivian President Victor Paz Estenssoro last year summoned the U.S. Army to assist local police in antidrug sweeps. Now, the Bolivian leader is trying to overcome stiff political opposition to a plan to eliminate most coca cultivation in his country over several years.

One motivating factor for this stepped-up Latin American crusade has certainly been U.S. pressure. Millions of dollars in U.S. foreign economic assistance are conditioned on participation in the war on drugs, and the Drug Abuse Act passed last year made even more emphatic the link between aid and performance on narcotics control. Failure by South American governments to meet eradication and other antidrug targets now risks the loss of economic and military assistance and leaves the countries open to U.S. trade sanctions and possible cut-offs in loans from multilateral development banks.

But another reason for action by South American governments stems from a recognition that the drug business is no longer just a U.S. dilemma. The narcotics culture has bred violence, corruption and political unrest in these countries. It also has spawned an addiction problem among local youths who smoke coca-based substances. The anticocaine war is being waged on three main fronts here: eradication of coca plantations; crop substitution along with other economic assistance; and interdiction of processing facilities.

Eradication, predictably, has been unpopular with growers. No other cash crop offers the earnings that the sturdy coca plant does -- from $800 to $3,200 an acre. For countries where average annual earnings are well below $1,000, such sums represent small fortunes.

Several hundred thousand peasants in Peru, and a few hundred thousand in Bolivia, depend directly on coca production for cash income. Masses more are involved in smuggling necessary chemicals, macerating coca leaves, refining the resulting paste into cocaine and transporting the narcotic. Whole towns thrive on drug profits.

Eradication attempts have triggered strikes, sabotage and violence in Peru's Upper Huallaga Valley and Bolivia's Chapare, the main coca-growing zones. Uprootings of coca in both areas fell far short of last year's modest official targets.

Eradication teams working under police guard were able to destroy most of the coca in the immediate vicinity of Tingo Maria, once Peru's coca center. But peasants have started new plantations farther up the Huallaga.

Farm groups in Bolivia's Chapare are threatening armed resistance if the government mandates eradication there. "There could easily be more bloody confrontations," said Victor Hugo Cardenas, a congressman representing farmers.

Growers say they would voluntarily abandon coca if the United States could provide them with other adequate sources of income. But so far, U.S. and other international aid programs have not given communities much to bank on.

Some foreign-funded projects have even facilitated coca's spread. Peruvian authorities, for instance, recently discovered hundreds of acres of coca along a newly opened road built with World Bank money in the northeast province of Napo Putumayo.

Interdiction efforts, meantime, are proving little more than a nuisance for traffickers. U.S.-trained antinarcotics units, while larger and better coordinated than before, lack the weapons, the aircraft and the equipment to outgun or outmaneuver the drug barons.

When the U.S. Army briefly entered the fight in Bolivia last July, deploying 170 troops and six Black Hawk helicopters to airlift police in antidrug raids, cocaine dealers fled and coca leaf prices fell far below the $40-per-carga (100 pound bag) cost of production. But since the Americans withdrew in November, Bolivian forces, using six U.S. helicopters on loan, have not been able to sustain the pressure. Local coca prices have returned to profitable levels.

In Peru, five major anticocaine operations in the past year and a half have produced impressive results on paper: the confiscation of 1.5 million pounds of coca leaves and 162,580 pounds of coca paste; the destruction of 167 airstrips; the capture of 175 weapons and 22 aircraft; the destruction of 39 laboratories; the seizure of 400,400 pounds of chemicals; and the arrest of 82 people.

But according to Gen. Juan Zarate, commander of the antidrugs division of Peru's Civil Guard, traffickers are deftly adjusting to the raids. Labs are now smaller, more self-contained and portable. Their communication equipment is powered by solar panels. Their camouflaging is more expert. After deciding to strike back at the narcotics business, South American officials have rudely discovered the limits of U.S. backing.

"We've been very disappointed," said Gonzalo Sanchez de Lozada, Bolivia's minister of planning. "We came up with a radical eradication plan. But it will require the creation of employment alternatives for hundreds of thousands of peasants, and we have not been able to get the financing for these programs from the United States. We get the most unbelievable stories from the Americans."

Bolivia's plan calls for eradicating all but about 25,000 acres of coca within three years. Estimates of the acreage now under cultivation range from 80,000 to over 200,000. The amount that would be spared is considered the "traditional" coca crop that feeds a centuries-old domestic demand for the leaf. Indians chew it to ward off hunger, injury, pain and cold.

Bolivia says it is prepared to invest $60 million in the program and is asking for an additional $240 million in foreign assistance to help relocate coca growers and create economic alternatives for them. The Reagan administration has pledged roughly $100 million to the effort, according to U.S. diplomats in La Paz. West European commitments so far total less than that.

In Peru, increased antinarcotics assistance also has been slow in coming. Three rented U.S. helicopters and a fixed-wing surveillance aircraft arrived in April after months of requests by Interior Ministry officials.

Uncertain that they can ever defeat the drug trade, South American governments continue to depend on the stream of coca-dollars, even as their presidents remain personally committed to combatting cocaine. Peruvian authorities, for instance, have purposefully -- and pragmatically -- designed exchange rates and other economic policies to cash in on the illicit business.

This involves overvaluing the Peruvian inti, thereby increasing the amount of dollars that cocaine wholesalers must bring into Peru to cover production costs there. By one Peruvian estimate, this policy yielded an extra $300 million to $400 million last year.

Moreover, by keeping inti interest rates up, the Lima government has sought to lure coca-dollars into local deposits. Central Bank officials in Lima hope this year to soak up around $700 million of the drug money flowing through Peru's economy.

Bolivia receives an estimated $600 million in repatriated earnings from coca sales, equaling the country's legal export revenues. In Colombia, cocaine sales exceed those of coffee, the country's leading licit export.Because current strategies appear overwhelmed and in trouble, some combatants are urging more innovative uses of existing resources.

Bolivian authorities have wondered whether the United Nations could set up a rapid-deployment, antidrug strike force to operate in South America.

A U.N. official in La Paz has proposed establishing an international fund for subsidizing prices of crops planted in place of coca.

A senior administrative court judge in Bogota has called on the United States to legalize cocaine, suggesting this would undercut the Medellin cartel.

American officials tend to dismiss these ideas as politically unacceptable or impractical.

But to many in the region, what is impractical is the U.S. response to cocaine's rising tide, setting antidrug policy goals that are artificial and often unachievable.

"If the expectation of the U.S. Congress is that current efforts will lead to a significant reduction in cocaine supply, I think that's naive," said a diplomat in Lima representing one of the United States' North Atlantic allies. "The most one ought to hope for is that it will be tougher for the mafia to operate and harder for those on the margin to get involved."

Still, the fight goes on, largely because those leading it see no real alternative. "I told my government," said a West European diplomat in La Paz, "it's a war that in the end we cannot win but one we cannot afford not to fight."