Mozambique said today that it has broken up a major foreign espionage network with the explusion of four U.S. Embassy officials and the arrest of several other foreigners and Mozambicans. Three of the four Americans ordered expelled yesterday left Mozambique today and the fourth was to leave Friday.

U.S. officials sharply disputed Mozambique's charges and a State Department spokesman said on Wednesday the expulsions had been ordered after a Cuban espionage team has seized one of the Americans and tried unsuccessfully to recruit him as a spy.

[In Washington Thursday, The Associated Press reported U.S. officials announced that Arthur Zimmerman, a representative of the General Tire and Rubber Co. of Akron, Ohio, has also been detained by authorities in Mozambique, apparently in connection with the spying allegations.]

A State Department spokesman said Wednesday that the expulsions were viewed with "most serious concern" and it was thought "not coincidental" that the expulsion came shortly after a group of Americans who publish an anti-CIA bulletin had visited Mozambique.

The sudden and highly publicized expulsions marked an abrupt jolt in what have been progressively more cordial relations between the United States and the Marxist government of President Samora Machel.

Notwithstanding its ties with the Soviet Union and Cuba, Mozambique has been anxious to get financial assistance from the West for its underdeveloped economy. It won cancellation of a congressional ban on U.S. aid last year and the Carter administration had proposed at least $6 million in initial aid. A U.S. team that was in Maputo discussing aid at the time of the expulsion of the other Americans was promptly withdrawn, officials said.

The expulsions also came at a time of changing perceptions among blacks and whites in southern Africa about the role Washington will play in regional problems and conflicts during the Reagan administration. President Reagan spoke this week of the need to maintain good relations with "a friendly country like South Africa."

Reagan's views have given wide publicity in South Africa as an indication that his administration will exert less pressure for changes in South Africa's racial policies because of the country's percieved strategic importance in East-West relations.

The official Mozambican news agency, AIM, charged that the four expelled diplomats were asked to leave because of "proven activities in espionage, subversion and interference in the internal affairs" of Mozambique.

It said the alleged spy ring had been operating since before Mozambique's independence from Portugal in 1975 and was supplying South Africa with information about black exiles from that country who were living in Mozambique. In the past, Mozambique charged, the alleged ring had given information to the former white Rhodesian government of Ian Smith about facilities in Mozambique used by guerrilla leader Robert Mugabe, now prime minister of Zimbabwe.

It also accused the Central Intelligence Agency of supporting "counterrevolutionary activity in order to destabilize the independent states in southern Africa." This appeared to be a reference to an antigovernment resistance movement operating in Mozambique with the help from South Africa.

The action comes in the aftermath of a daring nighttime strike Jan. 30 by South African forces on Maputo offices of the anti-South African guerrilla movement, the African National Congress.

The scale of that operation, in which 30 guerrillas were killed and three taken prisoner according to South Africa, as well as the ease with which it was carried out, have raised suspicious in Mozambique that the South Africans had internal cooperation. Senior military and party officials have been accused of treason for alleged complicity.

Following that raid, the Soviet Union, which has a treaty of military assistance with Mozambique, said it would take steps to defend the country in the event of any future attacks from South Africa. Two Soviet warships were sent to Maputo to enforce the point.

AIM identified the four expelled American diplomats as second secretaries Frederick Boyce Lundahl and Louis Leon Oliver; communications officer Arthur Russel and Patricia Russel, his wife, who is a secretary in the embassy's political section. In addition, Lundahl's and Oliver's wives were expelled, AIM said, because they "took part in support operations."