Israel reacted with disappointment Wednesday after Secretary of State Colin Powell (search) confirmed he will meet with organizers of an informal Israeli-Palestinian peace treaty.

The comments by Zalman Shoval, an adviser to Prime Minister Ariel Sharon (search), were the latest expression of Israel's stiff opposition to the meeting, seen as a U.S. gesture toward the "Geneva Accord (search)" that Sharon has denounced.

On Tuesday, Israel's vice premier said it would be "mistake" if Powell goes forward with the meeting -- an unusually strong rebuke from Israel to its closest and most important ally.

Shoval, a former ambassador to Washington, conceded Israel cannot prevent Powell from meeting with the plan's Palestinian and Israeli authors, but said the effort would be counterproductive.

"I think the decision that Secretary Powell must make is ... what the American interests are," Shoval said in a phone interview from Italy.

"America wants to promote the 'road map' and those people in Geneva ... want to go in a different path," he added. "Therefore I think it won't be very helpful."

The Geneva Accord outlines concessions by Israel that Sharon's government has opposed in the past -- including removing most settlements from the West Bank (search) and Gaza Strip and dividing sovereignty in Jerusalem, claimed by both sides as their capital. The accord also severely limits any return of Palestinian refugees to lands in Israel, which has brought condemnation from some Palestinian leaders.

The "road map" is a formal U.S.-backed peace plan that Israel and the Palestinians have accepted in principle as a basis for negotiations. It envisions an independent Palestinian state by 2005, but leaves open to negotiation the specific issues -- such as borders -- addressed in the Geneva pact.

The White House on Wednesday said Powell was free to meet with the Geneva authors but underlined its commitment to the road map.

"The path forward toward peace in the Middle East is the road map," spokesman Scott McClellan said, adding that "the secretary of state will make determinations about who he meets with."

U.S. gestures toward the Geneva plan have been seen as an implicit criticism of Sharon's hard-line stance toward the Palestinians.

Powell has said he would meet with the Geneva accord's authors on Friday.

"It seems to me the more people who talk about the prospect for peace, the better off we are," he said during a visit to Morocco on Wednesday. He added that "our commitment remains firm" on Bush's plan.

Nonetheless, the meeting has infuriated many Israelis.

On Tuesday, Israeli Vice Premier Ehud Olmert said Powell would be "making a mistake" to meet the organizers, led by former Israeli Cabinet minister Yossi Beilin and Palestinian minister Yasser Abed Rabbo.

"I think he is not being useful to the process," Olmert told Israel Radio. "I am certain of his friendship (to Israel), but I would cast doubt on his judgment in this matter."

The Geneva Accord was launched at a gala ceremony in the Swiss city on Monday. It was the result of more than two years of talks between former Israeli and Palestinian negotiators.

Sharon described the agreement as subversive. Palestinian leader Yasser Arafat praised the deal, but has stopped short of endorsing it.

However, militant Palestinian groups have denounced the accord.

Palestinian negotiators returning to Gaza from the Geneva ceremony were confronted by about 200 protesters Wednesday.

The crowd, which included several armed men, chanted slogans and threw stones at the car of Palestinian legislator Hassan Asfour. Asfour, who did not attend the Geneva meeting but supports the accord, was not injured.

The agreement proposes borders between Israel and a future Palestinian state close to Israel's borders before the 1967 Mideast war, giving the Palestinians almost all of the West Bank and Gaza Strip and part of Jerusalem.

In Washington, Palestinian negotiator Yasser Abed Rabbo, a key plan architect, said Wednesday the proposal has widespread support as an alternative "to continuing bloodshed with the two nations heading from one disaster to another."

Israeli negotiator Yossi Beilin, warned "the opportunity for a two-state solution is becoming dimmer and dimmer."

The deal enjoys significant support among the Israeli public and has put pressure on Sharon to end three years of violence.

"One thing is inescapable: The peace agreement that will eventually be signed ... will be similar to this document from Geneva," commentator Avraham Tirosh wrote in Wednesday's Maariv daily.