Morocco gave the United States no advance word of its decision to send troops to aid Zaire's effort to repel invaders who have captured a large portion of the country's southernmost province, the State Department said yesterday.

Spokesman Hodding Carter III also said that the United States has not received a request from Morocco for permissions to use U.S. made military equipment in Zaire. Such a request is required by the terms of U.S. military assistance programs.

Morocco has been receiving increasing amounts of military aid from the United States and is one of Washington's closest friends in the Third World.

In the current fiscal year, the United States is providing $30 million in military sales credits and about $800,000 in military training assistance for Morocco. The administration's request for fiscal 1978 is for $45 million in credits and $1.2 million for training.

Spokesman Carter said the United States is not taking a position for or against the Moroccan intervention in Zaire. He reiterated U.S. policy that African and called the Nigerian diplomatic moves aimed at resolving the Zaire problem "vital and useful."

Carter said the Moroccan decision "underscores the serious nature of the situation in Zaire."

The extent of fighting in Zaire's Shaba province has been a matter of some debate. By most accounts, the Katanan invaders made their sizable territorial gains without much fighting or much resistance from the Zaire defenders.

Carter said the United States understood that the battlefield situation was "relatively quiet."

The spokesman said he had no confirmation of a Washington Post report that Egypt also will send troops to help Zaire. Another State Department source said there was no indication Egypt plans to send troops and that such reports are "premature, at best."

President Sadat told President Carter this week that he plans to send a factfinding mission to Zaire, spokesman Carter said. "We have no other reports" of Egyptian plans, he said. During sadat's just-concluded visit to Washigton, the Egyptian president expressed concern about Soviet and Cuban activities in Africa.

A Zaire announcement that China is flying 30 tons of emergency military suppl ies to Zaire and sending more by ship also can not be confirmed Carter said.

He added that the State Department has no information that any nation other than Morocco has decided to aid Zaire.