WASHINGTON (AP) _ The International Monetary Fund is drawing attention to a new drop in its lending to financially troubled governments, as 3,000 private and government financial leaders gather for its annual meeting.

Sessions with representatives from the fund's 151 member countries begin Thursday and continue through Oct. 1.

Though the United States is now also the world's biggest debtor, it does not borrow large enough amounts from the fund to require its government to impose austerity programs as many Third World governments have had to do.

The fund had about $41 billion outstanding in loans on June 30, down from $44.2 billion a year before. Its new lending during the year amounted to $4.08 billion, down from about $5.08 billion in the previous year.

This compares with a peak of $13.2 billion lent in 1983.

Commercial bank lending to Third World countries has also dried up in recent years, so that the traditional situation is reversed and billions of dollars are flowing out of them to richer countries, largely in the form of interest payments.

The fund's managing director, Michel Camdessus, is asking Japan, West Germany and other countries with large surpluses in trade for another $8.1 billion to be used as loans to 62 of the poorest countries at interest of only 0.5 percent a year. These are areas, most of them in Africa, where the average citizen earns less than $850 annually.

Official meetings of the fund and its sister organization, the World Bank, start Thursday when representatives of poor countries meet to work on their assessment of the world's economic situation. This ''Group of 24,'' known as ''G-24,'' will make its announcement on Saturday. On the same day the ''G- 7,'' made up of the wealthy industrial countries, is due to hold a meeting of its own behind closed doors.

The seven include the United States, Japan, West Germany, France, Britain, Canada and Italy. Its session is expected to follow one by ''G-5,'' the same countries with Canada and Italy excluded.

Two of the biggest and poorest countries, China and India, say they will not ask for any of the fund's new money. They have good credit and can borrow from commercial banks if they want to, though on much less advantageous terms.

Most of the poorest countries have low credit ratings and rely for new capital on loans and grants from richer governments and intergovernmental bodies like the fund. They want capital for investment in new equipment, bought largely from the United States and other industrial countries, that would enable them to produce more goods, create new jobs and raise their low standard of living.

The bulk of the fund's lending has gone to countries like Brazil and Argentina where incomes are considerably higher. Their governments' financial troubles get a lot more international attention.

A special issue of the fund's official ''IMF Survey,'' made available Monday in connection with the meetings, said part of the decline in the use of the fund's credit was due to a drop in new applications for loans.

''However, it was mainly a response to the continued large volume of repayments, which resulted from a concentration of Fund lending a few years earlier, both during and immediately after the international recession and the beginning of the world debt crisis,'' the publication added.

The current debt crisis dates from 1982, when Mexico announced it could not make any more payments on its debt without new help.

Brazil, the Third World's biggest borrower, has refused since February to make any interest payments and several other nations, including Peru, Ivory Coast and Sudan are also falling further and further behind.