Meanwhile the backers of an unofficial peace plan were due to hold talks in Washington with US Secretary of State Colin Powell despite warnings from Israel that such a meeting would be a "mistake".

A military spokesman said the 12 detainees had been expelled from the West Bank and sent to the Gaza Strip overnight. The Israeli Supreme Court had given the go-ahead for the expulsions on Thursday.

A Palestinian security source confirmed that the 12 had arrived in the Gaza Strip.

The Israeli spokesman said eight were members of the Palestinian radical Islamic group Hamas, three belonged to the smaller Islamic Jihad and the 12th was a member of an armed group linked to Palestinian leader Yasser Arafat's Fatah movement.

Representatives of Hamas and Islamic Jihad have gathered in Cairo for talks aimed at securing a suspension of attacks by armed factions against Israel.

Palestinian premier Ahmed Qorei was expected to join the talks which began Thursday in what one participant called an "extremely positive atmosphere."

Qorei and his new government want to secure a truce by the factions to use as a tool to secure a ceasefire with Israeli Prime Minister Ariel Sharon's government.

He is likely to focus his efforts on securing the adherence of Hamas and Islamic Jihad, which have carried out the bulk of suicide bombings since the Palestinian intifada, or uprising, erupted more than three years ago.

Meanwhile, Powell was due to meet former Israeli justice minister Yossi Beilin and ex-Palestinian information minister Yasser Abed Rabbo in Washington to discuss the unofficial Geneva Initiative peace plan which was launched on Monday in Switzerland.

Israel's Trade Minister Ehud Olmert, Sharon' official number two, has said Powell was making an "incorrect decision" by agreeing to meet the pair.

Sharon himself has dismissed the plan as "dangerous", insisting the US-backed "roadmap" is the only framework for peace talks.

Powell however has said it is "a quite appropriate thing for me to do as secretary of state", while US President George W. Bush said Thursday that Geneva could be "productive, so long as they adhere to the principles" of the roadmap.

The Geneva plan addresses some of the thorniest questions of the conflict, providing for a division of Jerusalem and the de facto renunciation of the right of return for Palestinian refugees.

Under the terms of the roadmap, which has made little progress since its launch in June, such issues are to be addressed at a later stage only after violence is halted and both sides have honoured a series of commitments.