An envoy of Zaire's President Mobutu Sese Seko said today that when Zaire renews its diplomatic relations with Israel, it will open its embassy in Jerusalem.

Following a meeting with Israeli Foreign Minister Yitzhak Shamir, Nimyaidika Ngimbi, director general of Mobutu's office, told reporters, "Of course, Jerusalem is the capital of Israel, isn't it?"

A Foreign Ministry spokesman said that during the meeting, Shamir suggested to Ngimbi that the Zairian Embassy be located in Jerusalem, and that Ngimbi offered no objection.

Zaire will become the first of 22 black African countries that severed relations with Israel at the outset of the 1973 Middle East war to restore formal diplomatic ties. The decision was announced by Mobutu Friday night in Kinshasa, and Ngimbi flew here to convey the decision to Shamir and Prime Minister Menachem Begin.

Foreign Ministry officials said Ngimbi told Shamir that Zaire was having difficulties with the United States and had, as a result, rejected U.S. aid. The officials said Shamir replied that some of the difficulties might have arisen from Zaire not recognizing Israel, and that this condition may now be alleviated.

Zaire is the second country in a week to indicate that it will open an embassy in Jerusalem, from which all of the 13 remaining embassies moved in 1980 following adoption by the parliament of a bill reasserting Israeli sovereignty over the eastern sector of the city, which Israel annexed after the 1967 war.

Costa Rica, which had transferred its embassy to Tel Aviv in August 1980, announced on Wednesday that it plans to move back to Jerusalem.