Global economic growth prospects continue to be sluggish, leading to the probability that direct private investment by richer countries in the Third World will again fail to show an improvement during the next year.

That is the conclusion of an analysis of the future investment climate contained in the annual report of the International Finance Corp., the private investment affiliate of the World Bank.

The IFC makes loans to promote investment in private and mixed public-private enterprises in 111 developing countries. Last year, the IFC reported it made 92 new investments -- a record -- -- totaling $920 million in 41 Third World countries.

Although that amounted to 7 more projects than were financed in 1986, the total was down from $1.16 billion in fiscal 1986. Nonetheless, the loan program still is on track toward a five-year loan target of $6.5 billion, according to Sir William Ryrie, executive vice president of the IFC.

The IFC had record income of $54 million in fiscal 1987, compared with $25 million in the prior fiscal year, according to the report. Ryrie said that the improved earnings "will allow IFC to sustain and improve the services it provides where they are most needed -- in those parts of the world where the risks of investment are greatest." The boost in income came mostly from capital gains made on the sale of older equity investments.

The $920 million that IFC advanced last year launched projects with a total cost of almost $4.4 billion, up from $3.6 billion in 1986.

Ryrie reported that the IFC is introducing advanced financial techniques used in the industrial world, such as swaps and variable-rate loans with interest-rate caps, to its Third World borrowers.

The report cites as an example a transaction in which the IFC borrowed fixed-rate yen in Japan, swapped them to a major bank for dollars carrying the London Inter-Bank rate (LIBOR), then loaned some of the dollars to a client company, while swapping the balance into fixed-rate West German marks to be loaned to another client company.

The IFC said that this deal enabled it to borrow below LIBOR, providing its clients a more favorable rate, at the same time matching their currency preferences.

The somewhat downbeat analysis of the private investment climate recounted the 1986 deterioration of the economic performance of developing countries because of the drop in oil and other commodity prices, at a time when the increased lending envisioned by the Baker Plan failed to materialize.

That plan, put forward by Treasury Secretary James A. Baker III in 1985, called for expanded commercial and bank lending to the Third World over a three-year period. But the IFC cited World Bank data showing that 109 debtor nations in 1986 actually paid out $30 billion more in interest than they received in net disbursements from official and private lenders.

The IFC said that foreign direct investment flows to capital importing countries in 1986 totaled about $10 billion, reflecting no improvement since 1983. But much of this money is moving to Asia, the IFC said, meaning that some African countries -- which are supposed to be the top priority of IFC -- are losing direct investment.

"Prospects for world economic growth are not expected to improve much, if at all, in 1987," the report said.