African governments will need at least $2 billion a year more in economic assistance for the next few years than current programs call for, according to a United Nations special advisory committee headed by British economist Sir Douglas Wass.

A unanimous report by the Wass committee to Secretary General Javier Perez de Cuellar put the need at $5 billion a year in addition to projected aid that was envisioned when the group began its study in mid-l987. Since then, however, new plans sponsored by the International Monetary Fund, the World Bank, and the African Development Fund have added about $3 billion to the pool of funds available to the hard-pressed African subcontinent.

Wass outlined a program for the additional $2 billion that would be split between debt relief and new flows of money.

Goldman, Sachs & Co. Vice President Robert Hormats, the American member of the Wass committee, said the recommendations were designed to be pragmatic, with a chance of being accepted by the donor governments, the IMF and the World Bank.

"This makes a sound and conservative case for a few critical programs," Hormats told a press briefing on the report. "The order of magnitude is realistic."

In his report to the United Nations, Wass said $5 billion a year would "simply restore the prospects for development and growth {in Africa} as of the early 1980s, which were already highly constrained in many countries of the region ...

"Five billion dollars a year may seem a large sum in relation to past and present aid to Africa. In 1988, it may also seem large to donor countries, many of which themselves are troubled with budgetary problems."

The report conceded that debt relief, which implies cancellation of part of a debtor's obligations, must be approached "hesitantly" because it would undermine the discipline of contractual obligations if it became a regular occurrence.

But the situation in Africa, where most of the debt is held by governments or mutlilateral institutions, is different from that in Latin America, where most of the debt is privately held, the committee said.

The Wass committee's debt relief recommendations included converting into grants subsidized official development assistance loans to African countries "that are unlikely to become creditworthy."

In addition, where the official debt has been rescheduled on generous terms by the Paris Club, a group of Western nations that are the major lenders to the Third World, more concessions should be made on principal and interest for the next three years if a country isn't likely to become creditworthy in the near future, the report said.

Another recommended form of debt relief -- for countries with better prospects of regaining creditworthiness -- is rescheduling on the usual year-by-year basis, but at below-market interest rates.

On new flows of money, the committee urged the usual replenishment of International Development Assistance (IDA) and African Development Funds, as well as an improvement on a new IMF facility, which was recommended recently by Treasury Secretary James A. Baker III to finance balance-of-payment shortfalls among low-income countries.

The Wass proposal, building on a compensatory financing facility (CFF) within the IMF, would provide not only low-conditionality, but also put it on a "relatively automatic basis."

The Wass CFF would subsidize the rate of interest through grants by the richer countries, or by a sale of IMF gold. "Pending the {ninth} review of IMF quotas {a proposed addition to IMF resources}, access to the CFF should be increased substantially," the report said.