Despite continued skittishness in banking circles over loans to Third World countries, a top State Department official yesterday told Congress the chance of widespread defaults is slim.

"Aside from (Zaire), and one other small African nation, there are no official debt reschedulings currently on the horizon," Robert J. Ryan Jr., director of the Office of Monetary Affairs, told a House subcommittee on international development.

Ryan, who said his views reflected a consensus of opinion in the Carter administration, said he was optimistic about loans to less developed countries (LDC) largely because of new international financing facilities being planned by the International Monetary Fund and other lending groups. He also said that Zaire's default in 1975 taught investors how better to anticipate problem areas.

The major difficulty now, Ryan added, is in collecting accurate financial statistic from the LDCS - although he noted that it is sometimes harder to get the right numbers from the developed nations.

Asked by Rep. Michael Harrington (D-Mass.), the subcommittee chairman, whether the State Department is looking at any "potential totterers" in particular, Ryan replied, "I'd rather not single out any countries."

Higher worldwide oil prices and the recession of 1974-75 severely strained the LDCs. Their balance of payments deficits balloned, and many of them have been borrowing heavily to pay off enormous loans.