Iran threatened to start full-scale uranium enrichment if members of the U.N. nuclear watchdog agency press for U.N. Security Council action over Tehran's nuclear program at a meeting that opened Monday.
A top U.S. diplomat, meanwhile, said there was an urgent need to confront Iran's "clear and unrelenting drive" for nuclear weapons.
Iran "must be made aware that if it continues down the path of international isolation, there will be tangible and painful consequences," John Bolton, the U.S. ambassador to the United Nations, told the conference of the American Israel Public Affairs Committee on Sunday.
The International Atomic Energy Agency's 35-member board was not likely to discuss the Iran issue until Tuesday or Wednesday, but delegates said that whatever step the council might take would stop far short of sanctions.
India's prime minister said Monday that more time was needed for diplomacy. India, a member of the IAEA board, has long-standing ties with Iran, and Prime Minister Manmohan Singh told lawmakers in New Delhi that "confrontation should be avoided at all costs."
Singh did not say which way India would go if the IAEA meeting came down to a vote over whether the Security Council should take punitive action against Iran. Indian officials have said they do not want Iran to develop nuclear weapons, but Singh was criticized by left-wing political allies after India in February supported an IAEA resolution referring Tehran to the council, which is authorized to impose sanctions.
Iran's government warned Sunday that putting the issue before the Security Council would hurt efforts to resolve the dispute diplomatically.
"If Iran's nuclear dossier is referred to the U.N. Security Council, (large-scale) uranium enrichment will be resumed," Iran's top negotiator, Ali Larijani, told reporters in Tehran. "If they want to use force, we will pursue our own path."
He said Iran had exhausted "all peaceful ways," and that if demands were made contrary to the Nuclear Nonproliferation Treaty, the nation "will resist."
Larijani said Iran would not abandon nuclear research or back down from pursuing an atomic program that Tehran insists is only for the peaceful purpose of generating electricity.
IAEA delegates suggested the U.N. agency's board would not push for confrontation with Iran, and said any initial decisions by the Security Council based on this week's meeting would be mild.
The council's most likely action, they said, would be a statement urging Iran to increase cooperation with IAEA inspectors and to resume its freeze on uranium enrichment -- an activity that can make both reactor fuel and the core of nuclear warheads.
Even such a mild step could be weeks down the road, but it would formally begin council involvement with Iran's nuclear file, starting a process that could culminate with political and economic sanctions.
Bolton said a failure by the Security Council to address Iran would damage the council's credibility. "The longer we wait to confront the threat Iran poses, the harder and more intractable it will become to solve."
Russia and China, which can veto Security Council actions, are for now opposed to imposing sanctions against Iran, though they share the concerns of the United States, France and Britain -- the three other permanent council members with veto power -- that Iran could misuse enrichment for an arms program.
But Russia and China have economic and strategic ties with Tehran. While they voted with the majority of IAEA board members at a Feb. 4 meeting to alert the council to suspicions about Iran's nuclear aims, they insisted the council do nothing until after this week's IAEA meeting in Vienna.
Russia is unlikely to agree to strong action while it negotiates with Iran on a plan that would move Tehran's enrichment program to Russian territory.
Russian Foreign Minister Sergey Lavrov is due in Washington and New York this week to discuss the status of those talks with Bush administration officials and U.N. Secretary-General Kofi Annan.
Both Tehran and Moscow have said new talks are planned, though no dates have been announced. Iran rejected an EU proposal last year to end enrichment in return for the West providing reactor fuel and economic aid.
Past IAEA board meetings have ended with resolutions taking Iran to task for hindering investigations into a nuclear program that was kept secret for nearly 18 years and more recently urging it to reimpose a freeze on enrichment.
The Feb. 4 resolution asked IAEA chief Mohamed ElBaradei to report those concerns and others to the Security Council and to formally hand over the complete Iran file to the council. It also asked him to provide the council with his latest report, drawn up for this week's IAEA meeting.
That report said Iran appeared determined to expand uranium enrichment, planning to start setting up thousands of uranium-enriching centrifuges this year.