A program to promote economic development in the Third World while boosting U.S. exports of technology has been set up under the U.S. International Development Cooperation Agency.

The IDCA is the agency responsible to the president for economic relations with developing countries. Government units under its umbrella include the Agency for International Development and Overseas Private Investment Corp.

The new trade and development program is designed to help private companies in the United States break into Third World markets for such things as energy development projects, food production, mineral extraction and refinement.

It will spend $4 million in fiscal 1981 on feasibility studies commissioned by the developing countries for projects which can be carried out by private industry or U.S. government agencies.

The program will arrange "financial packages of project planning assistance, guarantees and export credits," IDCA Director Thomas Ehrilich said yesterday. It has had support from Congress for its emphasis on involving private firms in development projects, said Ehrlich.

"The trade and development program will enhance both development in Third World countries and the competitive position of the United States vis-a-vis our European and Japanese allies who use similar vehicles to gain a greater share of contracts for overseas projects," he added.

Although the program was set up only Tuesday under the IDCA, it will continue much of the work of its predecessor, the Agency for International Development's Office of Reimbursable Development, headed by David A. Raymond, who becomes acting director of the new trade and development program.

The program's budget is expected to expand rapidly over the coming years. Raymond pointed yesterday that the old program had increased its budget to $3.8 million this fiscal year. Over the last six years, it spent $5.8 million, including outlays on administration.

The developing countries commissioning the projects will pay for them out of their own resources, not out of special aid receipts. This will limit the projects, on the whole, to so-called middle-income developing countries.

Raymond said yesterday "a strengthened trade and development effort such as one planned should result in far greater U.S. export sales as well as progress in developing countries." He said that the steel industry, for example, could win construction contracts in the developing countries.

The new program still has a long way to go to catch up with similar ones carried out by other industrialized countries. Ehrlich said that Japan spends almost $60 million annually on similar program.