Sixty former U.S. diplomats have signed a letter to President Bush contending that his "unabashed support" for Israeli Prime Minister Ariel Sharon (search) is costing the United States "credibility, prestige and friends."

The letter expresses deep concern over Bush's April 14 endorsement of Sharon's proposal to pull out of Gaza (search) but keep some Israeli settlements in the West Bank.

"By closing the door to negotiations with Palestinians and the possibility of a Palestinian state, you have proved that the U.S. is not an evenhanded peace partner," the letter said.

The number of diplomats who have signed the letter was disclosed by the office of Andrew I. Killgore (search), who was ambassador to Qatar from 1977-80. A co-author of the letter was Richard H. Curtiss, a former chief inspector of the U.S. Information Agency (search).

The former diplomats termed Sharon's proposal - which was rejected by his Likud party (search) this weekend - a "unilateral plan to toss away the rights of 3 million Palestinians, to deny the right of refugees to return to their homeland, and to retain five large illegal settlement blocs in the occupied West Bank (search)."

Sharon has said he will proceed despite the Likud rejection.

The letter said Sharon's plan defies U.N. Security Council resolutions calling for Israel's return of Gaza and the West Bank to Palestinians, and ignores international laws declaring Israeli settlements illegal.

The letter also says extensive U.S. negotiating efforts in recent months have focused on Israel while ignoring the Palestinians.

The administration insists that it has maintained consultations with the Palestinians all along.

Bush has said repeatedly that his goal is the establishment of a Palestinian state (search) that is at peace with Israel.

Palestinian Cabinet minister Saeb Erekat said the ex-diplomats' letter, and a similar one sent last week to British Prime Minister Tony Blair by former British diplomats, showed that "diplomats are aware of the complexities, the deterioration in the Middle East, and the consequences of such deterioration."

Erekat expressed hope that "President Bush would really look very carefully at this letter and change course."