Mohammed Ishtayeh, a member of the Central Committee of the dominant Fatah movement and a confidant of President Mahmoud Abbas, told Voice of Palestine radio that Blair was no longer trusted to be an impartial mediator.

His comments were the latest in a series of recent public complaints by Palestinian figures about Blair's effectiveness, but went further by calling for the envoy's replacement.

Ishtayeh said the Palestinians had also written to the "Quartet" of mediating powers which Blair represents — the European Union, United States, Russia and United Nations — to say its latest proposition for a resumption of stalled peace negotiations was too vague to be meaningful.

Quartet envoys were due to meet in Brussels on Sunday.

"We do not expect much of the Quartet. There is discontent with its envoy Mr. Tony Blair," Ishtayeh said.

"Our general evaluation of his efforts is that he has become of no use at all. He has developed a large bias in favor of the Israeli side and he has lost a lot of his credibility."

"We hope the Quartet will reconsider the appointment of this person," he added, in the most explicit public suggestion to date that the Palestinians now want Blair to go.

A spokesman for Blair said the comments do not reflect his conversations with the Palestinian leadership.

He said it was the role of the Quartet representative to interact with both sides "not least so that we can continue to deliver change on the ground for Palestinians to improve their quality of life."

British Defense Secretary Liam Fox has also questioned Blair's qualifications to be Middle East envoy.

"Given his record as prime minister of the UK, I'm not exactly sure what the great qualities are of Tony Blair to make him such an exceptional international statesman," Fox said.

Blair, who was Labour prime minister between 1997 and 2007, led Britain into the controversial US-led war in Iraq in 2003, as well as sending troops into Afghanistan as part of the NATO-led operation in 2001. He was appointed envoy for the Quartet in 2007.

On Saturday, Palestinian negotiator Nabil Shaath said: "His (Blair's) major worry is not to anger the Israelis, and therefore he ended up just selling their programs, their projects."