Two Fijian soldiers of the United Nations peacekeeping force in Lebanon were killed today after they were kidnaped by Palestine Liberation Organizatiion guerrillas in southern Lebanon, the U.N. command said.

A Fijian officer held with the two dead soldiers was released by the guerrillas, along with three other Fijian soldiers captured in an unrelated incident, said Timur Goksel, chief press officer of the U.N. headquarters in Nagura, southern Lebanon.

A total of 13 Fijian soldiers in the U.N. Interim Force in Lebanon (UNIFIL) have been killed since UNIFIL assumed its peacekeeping mandate in the area in June 1978. Twelve of them were killed in incidents involving Palestinian guerrillas and one died in a clash with Christian militias led by Maj. Saad Haddad.

Goksel said today's clashes began when a Palestinian guerrilla attempted to break through a UNIFIL checkpoint near Al-Bayad, about one mile north of the Fijian headquarters in Qana, and the UNIFIL troops fired warning shots.

The guerrilla said he would be back, Goksel said, and about 30 minutes later returned with reinforcements, who opened fire. One Fijian soldier was wounded in the leg and three Palestinians of Fatah, the mainstream PLO military organization, were wounded, one of them critically.

Goksel said that during the exchange, three Fijian soldiers were captured and led away. Later, just as talks between the PLO and UNIFIL were about to get underway in Tyre, the bodies of two of the captured Fijians were returned to UNIFIL. Goksel said the Fatah guerrillas claimed they were shot while trying to escape.

In all, 64 UNIFIL soldiers have been killed in clashes in southern Lebanon.