The international consensus that had allowed the U.N. Women's Decade Conference here to agree on scores of far-reaching feminist demands collapsed today when the United States refused to accept a resolution declaring that the Palestinian people have the right to self-determination.

The collapse threatens to turn this conference into a replay of previous women's conferences at which divisive political issues kept the United States and other western nations from ratifying manifestoes on women's rights.

Acting on direct orders from Washington, Alan Lee Keyes, the only man on the 33-member U.S. delegation, informed a closed negotiating session this morning that the United States could not accept language that declared that the Palestinian people have a right to create their own state.

"We are at a women's conference. We cannot negotiate fundamental questions of policy at this conference," Keyes said in explaining the U.S. refusal to accept what he called "a tendentious political formulation" that could affect negotiations toward a Middle East peace settlement.

The flat U.S. refusal to negotiate any further on the Palestinian issue marked the abrupt end of a working consensus among the 157 countries attending the conference.

Since the conference began 10 days ago, that consensus had approved more than 350 paragraphs of a final report that reads like a Magna Charta of women's rights and reflects the degree to which the women's movement has gained ground throughout the world during the past decade. The Nairobi conference was convened to appraise the progress of women since 1975, when the U.N. Decade for Women was declared.

"Up to this morning we were trying to work for a consensus. Now the ball game has changed," said Munir Akram, a Pakistani delegate to the conference and chairman of the negotiating group in which the United States raised its objection.

The U.S. veto of the Palestinian resolution angered and embarrassed the Egyptian delegation, according to Akram. Egypt had been pressing compromise language that deleted any critical references to Israel. A senior western diplomat said the U.S. action also irritated delegations from Australia and Canada, normally allies of the United States on issues related to Israel.

"The resolution didn't challenge Israeli borders or condemn Israel," the western diplomat said. "It only said the Palestinians deserve a homeland. That isn't a departure from U.S. policy."

The U.S. position is that there should be no independent Palestinian state in the West Bank and Gaza Strip but that Palestinians should be given "full autonomy over their own affairs" and should exercise "self-government . . . in association with Jordan."

The Nairobi conference, scheduled to end Friday, has been widely praised by delegates from all regions, including those from the United States, for reaching agreement on a number of major women's issues.

The portions of the report approved so far call for government-funded day care, more sharing of housework, expanded leave for new parents, tough laws on violence against women and legislation forcing governments to take into account the economic value of housework.

"There has been far more serious work on women's issues in Nairobi than at the other women's conferences," American feminist Betty Friedan said, referring to those in Mexico City in 1975 and Copenhagen in 1980. Both were dominated by political issues, particularly the issues of a Palestinian homeland and condemnation of Zionism. The United States refused to sign the final reports at both.

If such language is added here, the U.S. delegation says it will again vote against the final document, most of which is otherwise acceptable to the U.S. government.

The United States and other western countries have said this conference should discuss political issues only as they affect the "unique concerns of women."

Keyes said today that it was not the United States but others that had derailed the conference, by insisting this week that the final report condemn Zionism.

Keyes, a "technical adviser" on a delegation headed by Maureen Reagan, whose father is the president, has emerged as the major policy spokesman on the U.S. delegation.

Among the draft provisions on which no consensus had been reached today were a condemnation of developed countries for "coercive measures" that harm economies of Third World states, economic sanctions against South Africa and condemnation of Zionism.

Akram said the condemnation of Zionism could have been deleted from the final report if agreement had been reached on the Palestinian homeland issue.

"Our whole effort was to get something on Palestine that we could take to the Arab countries and say, 'For God's sake, do you want a word Zionism or do you want substance?' " he said.

Reagan said at a press conference today that the United States will not sign the final document if it condemns Zionism, and without adoption by consensus, she said, "it is not a world document."