BEIRUT, Lebanon - Israeli helicopter gunships targeted Lebanon's largest Palestinian refugee camp yesterday, widening their 6-day-old onslaught against Iranian-backed guerrillas. Israeli aircraft also bombarded Beirut, killing a 2-year-old girl, after a rocket attack on northern Israel.

Despite a flurry of diplomatic activity involving the United States, France and other countries, there was no sign of a letup in Israel's offensive aimed at stopping the rocket attacks by Hezbollah guerrillas.

From hideouts in the valleys of south Lebanon, the guerrillas fired more volleys of Katyusha rockets into northern Israel, drawing more Israeli airstrikes.

Five civilians, including the 2-year-old girl, were killed and 20 wounded yesterday. All told, 46 people have been killed - including three Hezbollah guerrillas - and 166 wounded on both sides since the hostilities began Thursday.

Most of the dead have been Lebanese civilians.

Among the wounded was a Fijian captain with the U.N. peacekeeping force in south Lebanon, who was shot Monday when he challenged guerrillas preparing to fire rockets on Israel, the U.N. force said.

The attack before dawn yesterday on the Ein el-Hilweh refugee camp near the port of Sidon was the first on a Palestinian target since Israel began the offensive. The three Cobra gunships fired six rockets, gutting the house of Palestinian guerrilla leader Col. Munir Makdah, who escaped unhurt, police said. Two of his bodyguards and one of their wives was wounded.

Makdah opposed the 1993 peace accord between the Palestine Liberation Organization and Israel, and broke from the group to form his own militia. He later allied with Hezbollah.

Israel hopes its raids, which have forced 400,000 refugees - 10 percent of Lebanon's population - to flee north toward Beirut, will pressure Lebanon and Syria, the dominant power in the country, to disarm Hezbollah.

For years, Hezbollah has attacked Israeli troops and fired rockets at northern Israel to drive Israeli troops from a zone in southern Lebanon they control to curb cross-border attacks.

The guerrillas fired a barrage of Katyusha rockets on Israel's northern Galilee panhandle again yesterday morning. Israel army radio said the rockets crashed in northern Israel, causing damage but no casualties.

Hours later, three Israeli helicopter gunships swept through a curtain of anti-aircraft fire to hit Hezbollah targets in the densely populated Shiite quarter of Hay Sullom near Beirut International Airport.

They fired four rockets, damaging several buildings. Hezbollah guerrillas sealed off the area, roughed up journalists and tried to confiscate cameras and film.

A 2-year-old girl died from severe head wounds and two other civilians were wounded in that raid, police reported.

An Israeli military communique said the air raid, Israel's sixth on Beirut since Thursday, targeted a Hezbollah ''regional headquarters'' and pilots reported ''good hits.''

Meanwhile, long lines formed in front of Beirut bakeries and gas stations in a sign of the increasing panic among the city's 1.2 million people.

Israel's air force and artillery also struck villages in southern Lebanon and suspected guerrilla bases and infiltration trails on the edge of the Syrian-controlled Bekaa Valley in the east.