President Jose Lopez Portillo intends to raise with President Carter the smuggling of nearly $1 billion yearly in American goods into Mexico, an issue he says "is just as serious or even more serious" than the flow of illegal immigrants northward across the border.

The smuggling traffic produces millions of dollars in profits for American merchants and Mexicans feel the U.S. government has little interest in stopping it.

Lopez Portillo said in a recent interview that the flow of contraband means millions of dollars' worth of losses to Mexico in uncollected import duties and seriously hurts Mexican industry, exacerbating unemployment. "I'd really like to raise the American consciousness about that," he said.

President Carter is to arrive Wednesday for a 48-hour stay.

The Mexican president is not blaming the U.S. government. "Just as I cannot stop my undocumented people, there's the illegal trade and it's Mexico's responsibility for letting it pass," he said.

But Mexican customs officials want information from their U.S. counterparts to help stem the flow. "We'd like to see an American effort like the one we made to stop Mexican drugs," said Lopez Portillo. "What we did in drugs has been gigantic, much more than the U.S. itself."

Just as American marijuana smokers have long preferred "Acapulco gold" over the homegrown varieties, Mexicans prefer the price and quality of American toiletries, luxury goods and appliances.

A vast network of smugglers, not unlike that of the drug rings, operate all over Mexico. Professionals rent planes to unload their good on private landing strips or stuff trailers and wagons full of contraband for the trip across the border.

It passes customs on falsified papers or after runners pay considerable bribes to Mexican customs officials, according to the national director of customs, Ignacio Madrazo. Given the right contacts, a person in Monterrey or Guadalajara can order an American refrigerator, a stereo set or even a set of pistols and have them delivered.

A downtown Mexico City slum called Tepito until recently had its streets lined with hundreds of stalls selling contraband or stolen goods but police crackdowns have practically dried up the trade there.

"The contraband business is really staggering. We obviously have no accurate statistics," said customs director Madrazo, "but we reckon smuggled goods worth nearly $1 billion enter Mexico every year."

Mexico's National Chamber of Electronics Manufacturers estimates that 40 percent of Mexico's consumption of electronic wares comes from contraband.

Based on 1977 U.S. customs statistics, Madrazo said, $7.5 million worth of color televisions crossed into Mexico from the Laredo district of Texas alone, while Mexican customs in the same area only registered entry of $1.6 million worth.

Much of the contraband, Mexican officials say, originates in American duty-free stores that line the border from the Pacific to the Gulf Coast. The shops deliver the goods, sold untaxed, to airports or crossing points and provide U.S. customs proof that goods have thus left the United States.

From then on, the problem legally is Mexico's although many storekeepers admit that the sole purpose of their business is the trade with Mexico.

In Laredo, for example, merchants made sales for a record $470 million in 1978. One storeowner who does a brisk trade in tape decks, calculators and radios admitted to a reporter that if he depended on local patronage, "I simply would not be here."

Mexican officials want information from their U.S. counterparts about volume, types of products, points of departure and ceclared point of entry in Mexico of logal exports.

Eventually they hope for a change in U.S. rules for the duty-free stores in the border towns. "If the American shops needed to demonstrate their goods were legally imported into Mexico, it would be a very different game," customs director Madrazo said.

Although gunrunning and smuggling of liquor, cigarettes and luxury goods into Mexico is said to be as old as the border itself, and crack downs and cleanups have come and gone, Lopez Portillo's administration appears to be making a determined new effort to stop the flow.

As a former minister of finance Lopez Portillo is keenly aware of the lost income represented by contraband goods. Last year he appointed Madrazo, with a reputation for being honest and tough, as customs chief. Madrazo in the last few months has brought charges against three high-level and six medium-level customs officials.

Madrazo admits much of the work has to be done in Mexico itself. "We need not only more honest but also better qualified people," he said in a recent interview.

Many Mexican businessmen resort to smuggling as a result of the very import restrictions designed to protect them from foreign competitors. Mexican import duties not only are high but the bureaucracy may take up to two months to approve an import license. Since Mexico's technology is mostly American, industry depends widely on American spare parts.

Mexican businessmen are often heard to say that instead of waiting for an import license, they might as well bribe a customs official and get parts directly.

The Lopez Portillo administration is trying to speed up the import paperwork in addition to cracking down on customs officials taking bribes.

But U.S. help is needed. "It's obviously in the interest of both countries," said Madrazo. "The more contraband come in, the less jobs there are in Mexico and the more Mexicans will go illegally to the U.S. The problems are completely intertwined. It doesn't take an expert or a political sophisticate to figure that out."