Hamas prisoners leave jail in Nablus

In one incident, members of the group walked out of a prison in the West Bank town of Nablus, as hundreds of supporters demonstrating outside the jail made new threats against Israel.

The almost 1,000-strong protest was demanding the militants be freed to help with the fight against Israel.

"If you want Israel to swim in a pool of blood, start releasing out prisoners," one supporter shouted into a megaphone.

Fears

There were reports that guards had acted on their own in releasing the militants from jails in the West Bank and Gaza because they feared for the prisoners' safety.

In Gaza, some 350 prisoners were freed, among them scores of Islamic militants.

"All the prisoners left the Palestinian jails because the Palestinian Authority cannot protect them there," Hamas leader, Ismail Hanieh was quoted by the Associated Press news agency as saying.

This is a grave act and increases the probability of terror attacks

Israeli Prime Minister Ehud Barak

The Israeli leader's top adviser, Danny Yatom, accused Palestinian leader Yasser Arafat of making a mockery of his commitment to fight terrorism.

Interim peace accords between the Israel and the Palestinians have hinged on the premise that Israel would arm and co-operate with the Palestinian police force.

In turn, Palestinian security forces were expected to look out for Israel's security interests and prevent Islamic militants from carrying out terror attacks against Israeli targets.

"The Palestinian Authority has committed to fight terror and the terror infrastructure, not just before us but before the CIA and the Americans," Mr Yatom said.

Hamas and Islamic Jihad - members of which are also reported to have been released - are staunch opponents of peace with Israel.

Reports say the two most senior Hamas militants held by the Palestinians, Mahmoud Abu Hannud and Mohammed Dief, were not set free.

There are widespread fears that violence will break out after Muslim Friday prayers and ahead of the Jewish holiday of Sukkot, which starts on Friday night.