The head of the U.S. aid program for Latin America will propose today in Miami that private American banks join in a partnership with the Agency for International Development that could quadruple current assistance to the area.

Speaking before bankers and financial officials at an Inter-American Symposium on Finance and Credit, Abelardo Valdez will propose that American banks match dollar-for-dollar AID's program for the area. The aid program curently runs to $200 million annually, but Valdez proposes to double it by relending the nearly $200 million now flowing into the U.S. Treasury each year as payments on past loans to Latin America.

By adding matching funds from the private banks, the aid money could be expanded to $800 million. There is no precedent for such a close collaboration between government and private lenders through AID, although loan guarantees -- which Valdez would offer the banks -- have been used in the past.

Use of the funds from repayment of past loans would require action by Congress, which several years ago specifically prohibited such recirculation.

Valdez, in the prepared text of today's speech, notes "one of the sad ironies of our current situation... that AID is taking out of Latin America in loan repayments nearly what we are putting in... at this fateful moment in the development of the region."

In an earlier interview, Valdez pointed out that the once large AID effort in the region has been cut back because most of the Latin nations are now defined as "middle income" and Congress has focused the program only on the poorest.

Cut off from AID's loans at concessionary rates, the Latin American countries are already heavy customers of major American banks. But these commercial loans are never made for the projects that Valdez argues are most needed: rural development, nutrition, education and job training.

"The blending of AID's very concessional funds with long-term commercial loans might provide the necessary degree of concessionality to better support those governments that want to expand their programs for meeting the basic human needs of all their citizens," he said, pointing out that despite the "middle income" label, "half of the region's 320 million people live on average incomes of less than $200 a year."

In numerous speeches, Valdez has stressed what he sees as the danger of AID abandoning the middle-income nations. A recent symposium here on Mexico also focussed on the needs of these countries.

Although the House Committee on International Relations has shown some interest in the problems of the middle-income countries, neither Congress not the administration until now has acted to increase funding.

The program outlined by Valdez is to be submitted to the House committee in response to a request for such proposals incorporated in this year's aid act.

Valdez is hopeful that a positive response from the bankers to his partnership approach will generate congressional support. "I think the bankers' interest, too, is in growth of the social sector, although they may not realize it," he said. If the destitute rural populations are not brought into the countries' modern development, "their profits will be limited in the future," he said.

"The wounds of economic stagnation and alienation have already begun to appear elsewhere in the hemisphere," said Valdez. "Its symptom is the millions of undocumented Latin and Caribbean workers who flee to the U.S. as refugees from despair."

A Texan, Valdez is himself of Mexican origin. As assistant administrator of AID, he is one of the highest ranking Hispanics in the Carter administration.