The exiled leader of Hamas has warned that talks between Israel and the Palestinian Authority could be a 'fatal blow' to the Palestinian cause, and urged the Egyptian and Jordanian leaders to boycott them.

Khaled Meshaal, who lives in exile in Syria, said that Mahmoud Abbas, the Palestinian president, was too weak to stand up to Israel and negotiate a fair deal at the upcoming talks in Washington.

"If the talks succeed, they will succeed to Israeli standards and liquidate the Palestinian cause. They'll give us parts of 1967 lands. They'll draw the borders as they want and they'll confiscate our sovereignty," Meshaal said in a speech in Damascus on Tuesday.

Meshaal appealed to Hosni Mubarak, the president of Egypt, and King Abdullah of Jordan "not to back these negotiations, which are rejected by the Palestinians".

"The results of these negotiations will be catastrophic for the interests and the security of Jordan and Egypt."

Mubarak and the Jordanian monarch have been invited to Washington to join a summit on September 2, during which Israel and the Palestinian Authority are due to resume direct talks for the first time in 20 months.

The Palestinian Authority broke off negotiations with Israel in December 2008, when Israel launched a three-week war in the Gaza Strip.

Palestinians 'not bound'

Meshaal said the Palestinian people "will not feel bound by the outcome of these negotiations, because the Palestinian negotiators renounced their demands".

Hillary Clinton, the US secretary of state, announced earlier that the talks will be held without preconditions, and will run for a year.

Meshaal asked Abbas and his Fatah faction to join Hamas in adopting a unified strategy, which he said would not drop diplomacy but would concentrate on the "option of resistance and holding on to inalienable Palestinian rights".

Abbas's negotiation strategy has long been condemned by Hamas, which seized control of the Gaza Strip from the Palestinian Authority in 2007.

Hamas and Fatah have been estranged for years, and Egyptian attempts at mediation over the last few months have produced little progress.