At least four Palestinians were killed Monday and one seriously wounded in an explosion in the Gaza Strip.
Palestinian security officials say the men were killed when their car exploded near Khan Yunis in the Gaza Strip. Witnesses say the bodies were badly charred and the car was destroyed in the explosion.
The cause of the blast was not immediately clear, but witnesses say it may have been the result of an Israeli missile strike.
Witnesses say Israeli helicopters were flying over the area and tanks were maneuvering nearby at the time of the blast. A spokeswoman for the army says the Israeli military "has no knowledge of such an event."
During more than 16-months of violence, Israel has carried out a number of targeted killings it says are designed to stop Palestinian militants planning to carry out attacks on Israelis.
Palestinians call the killings "assassinations" and the policy has drawn international condemnation.
There have also been a number of incidents where Palestinian militants blew themselves up when bombs they were preparing exploded prematurely.
The car explosion took place hours after Israeli combat helicopters fired missiles at what the army says was a Palestinian mortar factory in the Jabalya refugee camp near Gaza City. The missiles destroyed the building, but there were no reports of injuries. The army says the assault was in response to mortar attacks in recent days on Israeli targets in Gaza.
Meanwhile, Israeli Prime Minister Ariel Sharon has dismissed Palestinian leader Yasser Arafat's latest call for an end to attacks on Israeli civilians.
Mr. Sharon says Mr. Arafat's pledge does not amount to a fundamental change in policy.
In an article published Sunday in the New York Times newspaper the Palestinian chairman condemned attacks by terrorist groups on Israeli civilians, saying such organizations do not represent the Palestinian people.
Mr. Sharon, who met last week with three senior Palestinian officials for the first time since coming to power a year ago, says he is willing to continue such meetings.
Mr. Sharon has severed all contacts with Mr. Arafat, and has confined him to his headquarters in the West Bank city of Ramallah since December.
The Israeli prime minister is scheduled to travel to Washington later this week for meetings with President Bush and other senior administration officials.