World Bank lending may rise nearly 90 percent to $21.5 billion annually by 1990, according to a new estimate by retiring President A. W. Clausen, who is pressing member governments for a new capital infusion.

To sustain lending at this sharply higher level and thus help spur economic growth in the Third World will require a general capital increase of $53 billion, Clausen said. He said the exact amount can vary with fluctuations in exchange rates.

Last year, the bank lent a total of $11.4 billion.

Clausen's recommendations are contained in a report he will make Thursday to the semiannual meeting here of the joint Bank/International Monetary Fund Development Committee. A copy of the document was made available to The Washington Post.

Under his proposal, the upper end of the range for projected bank lending would jump from $13.5 billion this year to an estimated $17 billion in fiscal 1987. That is $2 billion higher than the $15 billion "high case" possibility predicted at the annual World Bank meeting in Seoul last fall. For fiscal 1988, the lending target would rise to $19.5 billion, up $3 billion from the earlier estimate.

Clausen's report says that the bank management now puts the range of its loan programs for the fiscal 1986-88 period at $40 billion to $50 billion, instead of a $45 billion peak estimated in Seoul.

Similarly, for the following two years, fiscal 1989-90, the bank has raised its "high case" lending goal from $38 billion to $42 billion.

Clausen will tell the development committee -- which includes finance ministers representing about 150 countries -- that the increases stem from the realization that Third World countries will not be able to resume their growth without greater external aid.

"Paradoxically, if the debtors' capacity to service debt is to improve, debt must continue to rise for a time, albeit much more slowly than in the 1970s," according to Clausen, who will be succeeded at mid-year by former New York congressman Barber Conable.

Clausen cites bank studies showing that even if leading middle-income Third World countries institute the economic reforms demanded under the debt "initiative" launched by Treasury Secretary James A. Baker III, these debtors will need a net new flow of $70 billion to $105 billion in capital over the next five years, or an average of $14 billion to $21 billion annually.

This would be a reversal of the current trend: According to recently published debt tables, there was a net outflow of $22 billion from the borrowing countries to the lenders last year.

Despite the urgency of Clausen's appeal for new capital, a decision will not be reached next week. Baker is expected to reiterate at the Development Committee meeting that while the United States does not oppose a future capital increase for the bank, the United States believes the bank can expand lending for the next three years by roughly $2 billion a year over the 1985 level without new money. But many other leading nations back the Clausen proposal.

"During discussions of this report in draft with executive directors, there was widespread support for moving quickly to the opening of negotiations for a GCI," Clausen plans to tell the assembled finance ministers.

He also will urge them to support the financing of the bank's concessional aid program for the poorest Third World countries with a $12 billion commitment for the International Development Association for the three years beginning in 1987. This would represent a boost of $1.5 billion over $10.5 billion in the current IDA and IDA-related program -- $9 billion for IDA itself, plus a special $1.5 billion pool of money for sub-Saharan Africa on similar low- or no-interest terms.

But the U.S. commitment to the next concessional aid program, known as IDA-8, will depend on agreement that extra monies within a $12 billion IDA be disbursed under guidelines cooperatively established by the IMF and the bank. In any event, an administration official warned yesterday, IDA appropriations will be constrained by the realities of the Gramm-Rudman-Hollings deficit reduction law.

Clausen's report also contains a fervent plea for new and enlarged official assistance to sub-Saharan African countries, going even beyond the monies that would be contained in a $12 billion IDA.

An as-yet unpublished bank report says that about a dozen African nations face "a long-term trend of decline in . . . per-capita incomes." Clausen will tell the Development Committee that "the message" of this report is that the prospective economic and social decline of sub-Saharan Africa cannot be reversed without "medium-term programs of growth-oriented adjustment."

This new report calculates that the sub-Saharan African nations will need an additional $2.5 billion in new flows annually over the next five years, only $1 billion of which may be covered by a $12 billion IDA. The remaining "disbursement gap" of $1.5 billion a year, according to Clausen, might be met through bilateral aid, or conversion of official loans into grants