The United States has encouraged Nigeria to act as a go-between in the Zaire-Angola dispute to halt the Katangan invasion, according to diplomatic sources.

Tonight, the Nigerian foreign minister, after meeting with U.S. Ambassador Andrew Young here, indicated that his government would make the effort.

"We and other African friends are trying to see if we cannot get Angola and Zaire to straighten things out among themselves," said Nigerian Foreign Minister Joseph Garba.

If the Nigerian mediation, which diplomatic sources called an "encouraging" development, is successful it could ease a difficult situation for the Carter administration, which ahs been criticized by Congress for sending military support to Zaire. So far about $2 million worth of aircraft parts, medical supplies, parachutes, uniforms and other items, but no arms or munitions, has been sent and the State Department says it is considering Zaire's request for an unspecified additional amount.

Donald B. Easum, U.S. ambassador to Nigeria, is in Washington and is understood to be consulting in the negotiations.

U.S. Nigerian relations had been strained almost to the breaking point as a result of the Angolan civil war and at one point last year Nigeria realised to allow Secretary of State Henry A. Kissinger to visit the country. Relations improved markedly after Young visited Nigeria last month. Nigeria, which was among the [WORD ILLEGIBLE] countries civil war in 1975 and 1976, appears to have great influence with the Angolan government of [WORD ILLEGIBLE]

Katangans have been living in Angolan since the 1960s, when a bloody [WORD ILLEGIBLE] movement in the area then known as Katanga and now called Khaba Province, was put down by the Kaire central government.

Zaire has charged that Angola has aided the current invasion and that it is led by Cuban troops. Today Angola charged that Zaire's planes bombed three Angolan villages near the border last week.

The Nigerians, with the traumatic experience of putting down a separatist movement in Biafra behind them, feel strongly about the need for African governments to preserve their territorial unity.

Garba met yesterday in Washington with U.S. officials, including the Assistant Secretary of State of African Affairs William Schaufele Jr., and Garba met here today with Ambassador Young.

Before that meeting, Young told reporters that the "ideal" way to handle the Zaire problem "would be to have it handled by the Africans themselves."

Young pointed to Nigeria as the country with the most influence and the strongest interest in African unity and said, "If they could approach Angola it would be the best way."

American officials seemed today to take a more relaxed view about the incursion into Zaire by 2,000 and $6,000 former members of the Katanga constabulary. Katanga is the former name for Zaire's Shaba Province, the site of a bloody secessionist war in the 1960s.