The United States is in the process of training as many 300 Salvadoran military officers at its Panama Canal area military schools in how to deal with suspected guerrillas in their country while observing human rights.

The decision to begin the instruction, taken last summer without fanfare by the Carter adminstration and the military-civilian government it backs in El Salvador, is described by U.S. officials here as "extremely sensitive" and "experimental."

The training represents a significant compromise among the disparate elements of the Washington bureaucracy on the extent to which the United States should support the Salvadoran military and reinforce its ability to deal with a growing guerrilla opposition and control its population in an increasingly war-torn environment.

El Salvador for years has been a battleground between rich and poor, right and left. But in the past year, snce the Carter adinistration began taking an intense interest in its fate, it has become a center of confrontation among the State Department, the Pentagon and the intelligence community.

The training by U.S. personnel of Salvadoran lieutenants, captains and noncommissioned officers in Panama follows a heated debate within the administration last winter about plans to send three dozen U.S. military training teams into El Salvador to teach basic discipline and skills to the armed forces there.

That proposal, strongly supported by the Defense Department and the Central Intelligence Agency, was vehemently opposed by a number of State Department officials, including U.S. Ambassador to El Salvador Robert White, who argued that it would be intepreted in San Salvador as a return to U.S. counterinsurgency policy in Central America.

Already, the Panama compromise program is perceived in the region as further evidence of the United States' growing identification with El Salvador's increasingly conservative government, which took over from a rightist military dictatorship under promises of reform one year ago.

The training program has become the focus of an intense propaganda campaign on the part of Central American leftists, and U.S. officials fear it may complicate negotiations with Panama on the fate of U.S. military schools here, now that the transition to Panamanian control of the former Canal Zone has begun.

White, a career diplomat regarded as one of the toughest spokesmen for the administration's human rights and reform policy in Latin America, has been a central figure in the controversy throughout.

"White is the guy that is calling all the shots in El Salvador," said one U.S. military official here. According to both diplomatic and intelligence sources, White has opposed any major CIA or Pentagon interference in the policy the State Department has laid out for the country.

Soon after White arrived in El Salvador last April, he oversaw the replacement of the CIA station cheif at the embassy. These sources said that White has since discouraged the CIA's head of Central American operations from visiting the country.

Lt. Gen. Wallace H. Nutting, cheif of the U.S. Southern Command based in Panama and responsibile for the military security of the region, has asked to visit El Salvador on several occasions and has been told by White not to come because of "bad timing."

White essentially has maintained that the solution to El Salvador's problems will have to be political, social and economic -- that the military threat from the guerrillas trying to topple the U.S.-backed government is, over the long run, the least dangerous factor, and that the elements within the military itself may threaten the government.

Military and intelligence officials emphasized the need to back up the Salvadoran Army as much as possible.

"This is not purely a political problem," Gen. Nutting said recently. "There's violence, military action. The solution as it appears to me would be a political-military solution."

Nutting denied that he had any serious disagreements with White, said he was aware of the social and economic problems and expressed belief that steps should be taken to improve them.

Nutting did not see any possibility of direct U.S. military intervention in El Salvador.But he added, "Unfortunately a lot of people are unwilling to consider a more active involvement as a result of Vietnam . . . The problem is how do you manage the situation so they [the Salvadoran soldiers] aare left to do it themselves . . . My own view is that the Salvadoran forces need to improve their proficiency in a technical, professional sense, and if we can do that I think we should."

One way of doing this, planned as long as a year ago, was to send U.S. military training teams into El Salvador, fewer than 50 men altogether, to teach basic discipline and skills to the Salvadoran armed forces.

White vehemently objected to any such move."I just didn't want them in the country," White said in an interview. "It would involve the United States in an on-the-ground situation in a country in revolution and put us right in the middle." He added, however, that he had no objection to some forms of military aid.

White agreed to a plan to send $5.7 million worth of nonlethal military aid to the government.

In the months since, basic economic reforms have been put into effect. The Salvadoran left, which was growing ever more unified earlier this year, shows signs of breaking up along the old philosophical lines that kept it divided for most of the 1970s. The once broadbased civilian-military junta has grown increasingly conservative, with power now concentrated in the hands of the most conservative miltary commanders.

Since the beginning of the year, more than 6,000 person have died in the continuing political violence, most of them at the hands of Salvadoran military and paramilitary forces, though an increasing number are being killed by leftist revolutionaries.

A nationwide strike called by the left in August failed to demonstrate widespread popular support, and the insurgents have snce been on the political defensive, trying to prove both at home and abroad that they are still, as they have long claimed, the vanguard of the majority of Salvador's people.

Militarily, however, their initiative has not only retained its previous strength, it has grown stronger, and the left is on the offensive.

According to U.S. diplomatic and intelligence sources, as well as representatives of the guerrillas themselves, the revolutionary forces in El Salvador are better trained, better equipped and better able to mount major assaults on the Salvadoran government's troops than ever before.

Meanwhile, as one U.S. diplomat put it, "We haven't given this military a stick or a stone." Of the $5.7 million available in military aid, about $2 million has actually been used. Approximately $350,000 was set aside for training, and in the middle of last summer, the decision was made to use it for the Panama program, and training middle and lower level Salvadoran commanders -- the people who actually are in the field being killed and, historically, ordering most of the killing. Since Aug. 11, Salvadoran cadets, noncommissioned and lower ranking officers have been sent to Panama to receive from U.S. forces much the same instruction that the military training teams would have given them in El Salvador.

The three-week course at the U.S. Army School of the Americans at Ft. Gulic in the former Canal Zone is specially designed for Salvadoran soldiers. Although soldiers from all over Latin America have received training there since the mid-40s, Salvadorans had not been received at the school since the Carter administration cut off military aid to the deposed Salvadoran regime of Gen. Carlos Humberto Romero.

The course is titled Human Rights Aspects in Internal Defense and Development. Gen. Nutting described it recently as an effort to teach "how to be nice to people while you force them to do what you want them to do. How to assert force without being brutal."

The curriculum includes situational exercises where the arrest of a possible guerrilla is simulated, proper safeguarding and processing of suspected insurgents with respect for individual human rights, use of nonlethal tear gas and masks the United States has been sending to El Salvador, care of weapons, psychological operations (described as "civic action and how to be a nice guy," by one official), and histories of various insurgent movements.

So far 100 Salvadoran officers and noncoms have taken the course, according to U.S. military sources here. By the end of the year about 250 will have completed it. Another 40 are taking technical training, mainly in mechanics and equipment maintenance, at U.S. Navy and Air Force schools in Panama.

The training of Salvadoran troops in Panama is an extremely sensitive issue, according to officials there. The local press has been filled with sensational stores that U.S. troops are actually being readied for or are participating in combat in El Salvador. There are allegations of secret graveyards all kinds of exotic, brutal skills being taught. There is no substantiation to any of this, but the entire status of the Panama Canal Area Military Schools during the transition from United States to Panamanian control over the canal area has been brought into question.

If the Salvadorans can no longer train in Panama, one official said,"We may have to train them in the United States."