Secretary of State Condoleezza Rice Saturday urged Iran to return to negotiations with European Union countries, and to forever abandon plans for nuclear weapons. She made the appeal in a United Nations General Assembly address that also stressed the need to follow through on U.N. reform commitments.

The issue of what the United States contends is a covert Iranian nuclear weapons program has been prominent in the private contacts Ms. Rice has been having with foreign leaders on the sidelines of the U.N. meetings.

But the Secretary moved the matter to the forefront of her public agenda in the General Assembly speech, with a public call on Tehran to return to the talks with Britain, France and Germany that it broke off in August, or face Security Council action.

"When diplomacy has been exhausted, the Security Council must become involved," she said. "Questions about Iran's nuclear activities remain unanswered, despite repeated efforts by the IAEA. And after agreeing to negotiate with Europe, Iran has unilaterally walked away from the talks and restarted its nuclear programs. Iran should return to the negotiations with the EU Three, and abandon forever its plans for a nuclear weapons capability."

U.N. Secretary-General Kofi Annan brokered a meeting Thursday between EU Three foreign ministers and Iranian President Mahmoud Ahmadinejad.

There was no apparent progress, though the newly installed Iranian leader, making his debut in an international forum, is expected to announce some new proposals in a General Assembly speech later Saturday.

The Europeans have offered Iran economic and political incentives in return for an end to sensitive nuclear activities. The governing board of the International Atomic Energy Agency opens a critical meeting on the Iranian nuclear program in Vienna Monday.

The United States has been sounding out member countries of the 35-nation board about a referral of the matter to the Security Council for possible sanctions.

U.S. officials say most members are prepared to do so, though there are some key holdouts, including Russia, which says diplomatic options have not been exhausted.

Ms. Rice's speech, at the opening of the 60th General Assembly, was otherwise devoted to an appeal to U.N. members to follow through on commitments to reform, and create new agencies, including a peacebuilding commission and a reformed human rights agency that excludes human rights violators.

"The Human Rights Council must have fewer members, less politics and more credibility," she said. "And it should never, never empower brutal dictatorships to sit in judgment of responsible democracies. And, the Human Rights Council must have the moral authority to condemn all violators of human rights, even those that sit among us in this hall."

Secretary-General Annan, whose nine-year tenure as U.N. chief has been marred by scandals, including mismanagement of the Iraq oil-for-food program, opened the session with a promise to vigorously pursue the reform commitments, including more stringent U.N. budgetary controls.

"I intend to follow through on every action asked of me, and I ask you, the member states, to tell me immediately, if you think I am not doing so," he said. "I will also keep score on progress you make in implementing what has been agreed. And I will speak plainly, if I believe you are falling behind. And I have no doubt that global public opinion will keep a close eye on our progress."

Many of the reforms are to be implemented in the coming year, though discussions have been deadlocked on the key issue of expanding the U.N. Security Council. Mr. Annan's term ends in December 2006.