Gunmen on Friday kidnapped three Irish soldiers serving with the U.N. peacekeeping force in south Lebanon and demanded the release of a guerrilla leader abducted by Israel, police said.

In other developments Friday:-Peter Winkler, a Swiss official of the International Committee of the Red Cross who was kidnapped on Nov. 17, was released in the southern city of Sidon. He said he did not know who kidnapped him. Voice of Lebanon radio said Winkler was released by the Fatah-Revolutionary Council, the guerrilla group headed by Palestinian terrorist Abu Nidal.

-Police said eight fighters were killed and four wounded in Sidon when the mainstream Shiite Moslem Amal militia fought guerrillas of the Palestine Liberation Organization.

Friday's abduction was the second time in less than 24 hours that Lebanese gunmen captured Irish troops to retaliate for Israel's seizure of Jawad Kasfi.

In Jerusalem, the Israeli army said its soldiers in south Lebanon seized Kasfi, another senior local guerrilla commander and two other guerrilla suspects on Thursday.

Police said four gunmen in two cars seized the three Irish soldiers in Tibnin on Friday, bundled them into a white Mercedes and sped away. The village borders on Israel's self-proclaimed security zone.

Lebanese police said on condition of anonymity that the kidnappers demanded that the U.N. Interim Force in Lebanon, with which the three Irish soldiers served, negotiate with Israel for the release of the four guerrilla suspects.

UNIFIL spokesman Timur Goksel said the U.N. force has not negotiated with Israel so far.

"They (Israel) acknowledged that they are holding these people. This was our only official contact," Goksel said. "Of course, there was a very strong protest from UNIFIL because it was an infringement on UNIFIL zone. But we got no response to that."

The afternoon clashes at Sidon were touched off when two Palestinians were killed by a rocket-propelled grenade fired by Amal gunners near the Ein el-Hilweh Palestinian refugee camp, police said.

The battles with mortars, grenades and machine guns raged after nightfall on Sidon's southern outskirts, triggering fears of a major confrontation that would negate a 20-month-old Syrian-brokered truce.

Amal fought a two-year war with the Palestinians before the truce took hold. More than 1,500 people were killed and 3,500 wounded in the fighting, in which Syrian-backed Amal tried to prevent PLO chairman Yasser Arafat from rebuilding the Lebanon power base he lost in Israel's 1982 invasion.