A faction of the Palestinian militant group Islamic Jihad has claimed responsibility for a suicide bombing that killed an elderly Israeli woman Monday. But Islamic Jihad's spokesman in the Gaza Strip said his group is committed to honoring the ceasefire it agreed to two weeks ago.

The claim of responsibility for the bombing came from a branch of Islamic Jihad based in the West Bank town of Jenin. A statement issued there said the attack in the Israeli village of Kfar Yavetz was only the first and that more attacks would follow unless Israel releases all Palestinian prisoners.

But an Islamic Jihad spokesman in the Gaza Strip said the organization remains committed to the ceasefire they announced 10 days ago.

Israeli police had initially blamed a natural gas leak for the explosion that leveled the home of a 65-year-old woman. But after finding the body of an unidentified man in the rubble they began investigating it as a possible terror attack.

A police spokesman said they now have conclusive evidence that the explosion was a suicide bombing.

It is the first suicide attack since the three main Palestinian militant groups declared a temporary cease-fire on June 29.

The spokesman for Israeli Prime Minister Ariel Sharon said the bombing proved that the Palestinian ceasefire is worthless. Ra'anan Gissin said the ceasefire is not worth the paper it is written on and is no substitute for what he termed relentless real action to dismantle the terrorist infrastructure.

Meanwhile, Palestinian Prime Minster Mahmoud Abbas has canceled his Wednesday meeting with Ariel Sharon. Reports said that some people on the Fatah Central Committee, of which Mr. Abbas is a member, are dissatisfied with the way he has been handling negotiations with Mr. Sharon. They say he is too willing to make concessions and has little to show for his efforts so far.

Israel Radio reported one of the issues involves Israel's position on the release of Palestinian prisoners. On Sunday, the Israeli cabinet agreed to free about 350 Palestinians, but security officials recommended that no members of militant groups, be considered for release. Palestinians say such a policy could lead to a resumption of attacks on Israelis.

Reports quoting Israeli sources say that there will be no prisoner releases until both prime ministers meet.