Reagan administration officials are offering strong resistance to a proposal by the World Bank for an increase from $12 billion to $16 billion for its subsidized lending program for poor nations, suggesting instead a slash to as low as $9 billion.

These loans would be made by the bank's soft-loan affiliate, the International Development Association, for a three-year period beginning in mid-1984.

The staff's $16 billion proposal--for a program known as IDA-7--will be discussed for the first time at a meeting of the donor countries' deputy finance ministers in Tokyo July 19-21.

The United States will be represented by Assistant Treasury Secretary Marc Leland.

The Reagan administration's reported desire to whittle IDA-7 to a $9 billion level will be explored Thursday in a closed "consultation and briefing" session of a House Banking subcommittee, called by its chairman, Rep. Jerry H. Patterson (D-Calif.)

Leland and his deputy, Tom Dawson, have been asked to explain the Treasury view on IDA-7. Patterson and other concerned congressional Democrats reportedly are considering holding a public hearing if Leland and Dawson confirm the Reagan administration's intention to cut back IDA funds sharply.

World Bank President A.W. Clausen, after outlining the high priority he assigns to IDA at a meeting with President Reagan and other high administration officials at the White House on Monday, will have further discussions on the IDA issue and other World Bank affairs with Treasury Secretary Donald T. Regan today.

IDA offers long-term, interest-free loans, with only a small service fee, to the poorest World Bank member countries.

Sources said Treasury officials believe that a budget-conscious Congress will not approve annual U.S. contributions to IDA that exceed $750 million a year, sharply lower than the $1 billion-plus annual contribution to which the United States had been committing itself prior to the Reagan administration.

Since a minimum U.S. share of the IDA total that is acceptable to other donor nations is probably 25 percent (the U.S. share of IDA-6 is 27 percent), that would mean an annual IDA package of $3 billion, or $9 billion over three years.

A Treasury spokesman quoted Regan, who was present at the Reagan-Clausen meeting, as saying that the United States has not yet taken a public position on how large IDA-7 should be, "but we'll talk about it."

American officials who resist the bank's $16 billion proposal for IDA-7 note the difficulty in getting IDA-6, with a $12 billion total, through Congress. The original IDA-6 program was sent to Congress by the Carter administration.

The U.S. share of IDA-6 was to be $3.24 billion, appropriated over three years ending in fiscal 1983. But Congress appropriated only $500 million in each of the first two years, and $700 million so far in fiscal 1983, or a total of $1.9 billion, leaving $1.32 billion still to be contributed.

Reagan administration officials have asked Congress for a $245 million supplemental appropriation for fiscal 1983. But even if this is voted, it still would leave about $1.1 billion to be appropriated in fiscal 1984, or a fourth year for IDA-6.

Bank officials argue that, after the effects of inflation are taken into account, $16 billion would provide a real increase of only $1 billion. Moreover, the addition of China as a major IDA client means that all other IDA recipients will be taking a real cut in the aid provided.

According to administration officials, Clausen reviewed the need for continued development assistance to the poorer nations of the world during his meeting with Reagan. He cited not only IDA's role, but the need to expand the World Bank's capital to support increased loans to the more advanced of the developing nations.

Meanwhile, the bank estimated yesterday that its regular loans, together with IDA commitments, would increase to $15.4 billion in the year ending June 30, 1984, after having set a record at $14.4 billion in the year ended June 30, 1983.

In reporting on World Bank finances, Treasurer Eugene Rotberg said that short-term interest rates would be volatile for the rest of the year, sometimes higher and sometimes lower than they are now. The bank showed a profit of $752 million for the past fiscal year, up from $598 million in fiscal 1982.