World Bank President Barber Conable yesterday predicted that member governments would finally approve a much-debated increase in the bank's capital in the fiscal year beginning next July, thereby raising the bank's lending limits.

Conable said a general capital increase will be necessary to permit the bank's loan programs to grow "well into the 1990s." Bank officials have talked of the need to double the bank's existing capital of about $85 billion.

Conable also cautiously raised the possibility that the bank would consider some level of guarantees for a new security that would enable debtor countries to convert a portion of their commercial bank debt into bonds. The United States has opposed such an action on grounds it would shift the debt burden to the taxpayers in the countries funding the bank.

Other bank sources said it is unrealistic to consider widespread use of guarantees when the bank is close to its lending limit, which is equal to its capital. Guarantees are counted in the same way as loans when figuring how close the bank is to its limit.

In its annual report, released today, the bank complained that while its lending to the poorest countries was up 9 percent in the year ended last June and its loans to debtor countries targeted by the Baker Plan were sharply higher, the commercial banks have not been doing their share.

"Strong financial support from international institutions to countries undertaking adjustment programs has not been accompanied by any significant new financing from commercial banks," the report said. "New flows of aid and/or innovative debt-relief measures are needed to deal with the debt service problems in low-income sub-Saharan Africa."

The report predicted "another 12 months, at least, of slow growth in the world economy." It warned that with an expected reduction in the U.S. budget deficit, there could be a global recession unless there is "extra stimulus from Japan and Europe." Conable's comments about bank guarantees came in response to a question about a Brazilian debt conversion proposal. Conable said that while he is "happy, as always, to consider innovative new approaches," there should be "no expectations of major guarantees." When pressed about the possibility of some level of guarantee, he said there is "always that possibility." But he said it is unlikely that there will be "a massive change in policy."

Conable also told reporters that he sees an end to the morale problems at the bank stemming from its reorganization to weed out as much as 10 percent of its 6,000-personstaff. He defended the reorganization as necessary to boost efficiency and said "the process will be behind us by the time of the annual meeting" at the end of the month.

"There will be a resurgent morale -- the proof of the pudding will be in the eating," he said.

The annual report, and Conable's remarks, were a prelude to the World Bank-International Monetary Fund annual meeting and related conferences that get under way here late next week.

In the report, the bank charged that commercial institutions had not fulfilled commitments called for under the plan devised by Treasury Secretary James A. Baker III to help 15 major debtors: Argentina, Bolivia, Brazil, Chile, Colombia, Ivory Coast, Ecuador, Mexico, Morocco, Nigeria, Peru, the Philippines, Uruguay, Yugoslavia and Venezuela.

The plan, unveiled by Baker at the 1985 World Bank-IMF meeting in Seoul, suggested substantial new lending by both commercial and multilateral banks over a three-year period, along with basic economic reforms by the borrowing countries.

The bank said it is meeting its Baker Plan obligations, having increased disbursements to the 15 nations from $3.9 billion in 1986 to $5.9 billion in 1987. From 1981 to 1987, the bank said, its commitments to those 15 nations exceeded $33 billion, with almost half of that coming in the last three years.

But these countries have not been able to grow at a satisfactory rate, the bank report said, because commercial banks did not make an equivalent effort.

Overall, the bank reported a substantial boost in loan disbursements last year to $11.4 billion, ending a three-year period when disbursements were confined to a range of $8.3 billion to $8.6 billion after many years of steady growth.

Loan approvals rose to $14.2 billion last year, and in the current year -- fiscal 1988 -- are expected to range between $14.5 billion and $15 billion. Counting expected new credits of $4.2 billion from the International Development Association (IDA) -- the bank's concessional loan affiliate -- that would make total loan approvals and credits to be extended to the Third World a record $17 billion to $19 billion in fiscal 1988, the bank said.

The report noted that the bank's projections for lending in fiscal 1988 could put it over an internal benchmark, the "sustainable level of lending." This level, which is determined by the amount of the bank's capital, is $14.2 billion.

Conable and other officials have strongly favored a substantial general capital increase. But the U.S. government, alone among the major members, has resisted, fearing a negative reaction in a budget-conscious Congress.

The bank's 9 percent lending increase last year brought to $6.43 billion the total loans by the bank and IDA to countries with a per capita gross national product of less than $400 (in 1985 U.S. dollars.