Two Israeli officers were killed in Gaza Tuesday in the violent upsurge, which underlined obstacles to negotiations after an Egyptian peace envoy was accosted by Palestinian radicals who branded him a traitor for talking to Israel.

Egypt's Foreign Minister Ahmed Maher, who won a cautious Israeli offer of support for a Palestinian truce that Cairo is trying to broker, played down the incident at Jerusalem's al-Aqsa mosque and said the peace push would go on.

Palestinians said about 20 Israeli tanks rumbled into a refugee camp in Rafah overnight, drawing fire from militants. More tanks, firing machineguns, moved in during the day.

Israeli soldiers killed a 50-year-old man and two gunmen in the camp, medics said, adding another Palestinian was shot in the stomach and died in hospital.

One militant was brought dead to the hospital still clutching a bomb, witnesses said. Another died of shrapnel wounds. A Palestinian policeman was shot near the border post and an onlooker was killed as he watched tanks at his window.

The army said Tuesday's raid was not in response to the ambush in central Gaza late on Monday in which two officers died -- the first Israelis killed in a month. At least 25 Palestinians died in violence over the same period.

An army spokesman said the Rafah raid was "part of a continuous fight" to destroy tunnels to smuggle arms from Egypt. The army said one tunnel was found in a house. A similar operation in October took a week and left 15 Palestinians dead.

"Blood for blood and killing for killing," chanted thousands of Palestinians at funerals for the dead in yesterday's raid.

The al-Aqsa Martyrs Brigades, which lost two dead in the raid and was one of two militant groups behind Monday's ambush, vowed to strike back inside Israel. The group is linked to Palestinian President Yasser Arafat's Fatah faction.

The Jewish state has demanded a Palestinian crackdown on militant groups as a commitment to the so-called "road map" and warned of unilateral steps if it failed that would cost the Palestinians some of the land they want for a state.