Eritrean secessionist guaerrillas say they are holding Soviet and Cuban prisoners captured during their fight for independence from Ethiopia.

Al-Amin Mohammed Said, a spokesman for the Eritrean People's Liberation Front, made the claim in an interview published today by the independent daily An-Nahar.

Said gave no estimate of the number of prisoners held, but said: "Our forces buried many dead foreigners fighting with the Ethiopian troops."

The spokesman also said: "We have documents that prove the direct Soviet and Cuban military intervention." These had not been released up to now, he added, because they included military and strategic plans.

The Eritrean People's Liberation Front is one of three Eritrean groups that have been fighting for the independence of the Red Sea province since its incorporation by Ethiopia in 1962, but this is the first time it has referred to foreign prisoners.

Ethiopia, meanwhile, blamed President Carter for Somalia's invasion of Ethiopia and hinted that Addis Ababa might break relations with Washington.

Commenting on Carter's news conference last Thursday, Addis Ababa radio charged that the President's statements were indicative of U.S. plans to arm the Somalis to help them continue their invasion.

"It is known that Somalia was pushed into a war of invasion against Ethiopia by the U.S. government, and especially by President Carter," the broadcast said.

In his news conference, Carter criticized the Soviet Union's "unwarranted involvement" in Ethiopia and said the United States would refrain from sending arms to either side.

Carter suggested that a solution to the conflict should be found in the Organization of African Unity or the United Nations.

The Carter administration offered to supply Somalia with "defensive weapons" in July, but withdrew the offer when Somalia invaded Ethiopia's Ogaden region.

Addis Abba radio also said Ethiopia's military government has "liquidated" five leaders of a rival underground Marxist movement and arrested more than 300 persons in a drive to crush internal opposition.

The dead were identified as members of the Ethiopian People's Revolutionary Party, an organization of students, intellectuals and trade unionists who demand return to civilian rule.

In a related development, Saudi Arabian Foreign Minister Prince Saud, speaking in Tehran, pledged his country's aid to Somalia if its frontiers were violated by a foreign power.

The Saudi minister is visiting Iran for talks with the shah, who met earlier this week with King Khalid in Riyadh.