American diplomats will quit the World Conference Against Racism if anti-Israel provisions remain in its final declaration, Bush administration officials said Friday.

"We have made very clear that elimination of the offensive language singling out Israel is critical for the United States to be able to participate fully in this conference," State Department spokesman Richard Boucher said.

The assignment of the American team at the conference is to work hard, in the corridors, to remove provisions advanced by the Palestinians and their supporters that are designed to embarrass the Jewish state and label it a colonial oppressor.

So far a U.S. diplomat is seated at the American place in the conference room in Durban, South Africa, but he is not participating in the deliberations. Other Americans are trying to get the provisions changed.

If they fail, the Americans will leave before the weeklong conference ends, the officials said.

In the meantime, "We continue to look to the conference participants to effectively eliminate this inappropriate rhetoric from the documents of the conference, and we will continue to work actively to achieve that," Boucher said.

Secretary of State Colin Powell wanted to attend the conference. As the first black secretary of state, Powell thought the conference would have offered a chance to show that America can rise above racism.

But when preconference negotiations in Geneva, Switzerland, failed to knock out a provision likening Zionism, the religious and philosophical underpinning of Israel, to racism, Powell decided to boycott.

"The Secretary has kept in close touch with our representatives in Durban as they work these issues and has spoken frequently himself with the (U.N.) secretary-general, Kofi Annan, and others," Boucher said.

Members of the Congressional Black Caucus attended the conference and said in a statement: "The refusal of the government to send the highest ranking African-American in its history to engage the world in a discussion of racism is disrespectful of the sacrifices of all that have suffered to get him where he is."

A deputy assistant secretary of state, Michael Southwick, heads the U.S. delegation, which is assigned only the task of trying to get the anti-Israel language changed.

Israel and Canada also sent low-level delegations.

White House press secretary Ari Fleischer, explaining why American diplomats went at all, said President Bush "wanted to make every effort to clean up the language so that the racism conference did not have language that was anti-Israel or anti-Semitic."

"I can tell you that nobody is more disappointed that the conference took the turn it took than Colin Powell, who very much would have liked to have gone," Fleischer said.

Annan opened the conference with a plea for an international plan to combat prejudice.

Annan, who is black, from Ghana in West Africa, said the Holocaust made Jews sensitive to accusations of racism. Still, he said to applause, "We cannot expect Palestinians to accept this as a reason why the wrongs done to them -- displacement, occupation, blockade and now extrajudicial killings -- should be ignored, whatever label one uses to describe them."

The Rev. Jesse Jackson, a black American civil rights leader, said Friday the Palestinian delegation agreed to drop criticism of Israel and Zionism from the declaration. At the conference in a private capacity, Jackson telephoned Powell to discuss developments.

Palestinian officials later said Jackson had been "overzealous," and Yasser Arafat, leader of the Palestinian Authority, urged delegates to condemn Israel's "colonial, racist plot" against Palestinians.

Arafat deputy Nabil Shaath, author of the anti-Israeli provisions, said Israel engaged in "racist practices."

U.S. officials in Washington said they had not given up on eliminating all language attacking Israel and noted the conference had just opened Friday.