The United Nations nuclear watchdog has voted to report Iran to the Security Council over its nuclear activities.
Iran says its nuclear programme is only for producing energy
Twenty-seven states out of 35 on the IAEA board backed the move, with three against and five abstentions.
The decision follows days of intensive diplomacy and could lead to possible UN sanctions against Iran.
An Iranian official said Tehran would resume full-scale enrichment of uranium and Russia's compromise offer to enrich uranium on its own soil was in doubt.
Javad Vaiedi, deputy head of the Supreme National Security Council, said the vote was politically motivated, adding that there was no international consensus.
Tehran has also threatened to downgrade co-operation with the International Atomic Energy Agency (IAEA), and end any chance of a compromise on enrichment.
Iran denies it has been concealing efforts to develop nuclear weapons, maintaining its programme is only for producing energy and does not have a military aim.
'Iran should listen'
The resolution urged Iran to extend "indispensable and overdue" co-operation to the IAEA and help it "clarify possible activities which could have a military dimension".
But it puts off any action until a report is delivered by agency chief Mohamed ElBaradei at the next IAEA meeting on 6 March.
Russia and China agreed to support the resolution on condition it did not contain any immediate threat of sanctions against Iran.
Only Venezuela, Cuba and Syria voted against it.
India voted in favour of the motion in spite of the government coming under intense domestic pressure to stand by Iran.
US ambassador to the IAEA Gregory Schulte said the vote sent a "very powerful signal" and the ball was now in Iran's court.
"Iran, rather than threatening the world, should listen to the world and take steps to regain its confidence," he said.
The vote had been expected on Friday, but was delayed by an attempt by developing countries to soften the resolution, which was rejected by Germany, France and the UK, the countries proposing it.
Also, diplomats say Egypt made a proposal to include a reference to making the Middle East a nuclear weapon free zone.
This was rejected by the US, which saw it as an attack on Israel's nuclear arsenal.
But diplomats told AP news agency that Washington eventually agreed to the clause after it received overwhelming backing from European allies.
Iran recently decided to resume suspended research on uranium enrichment.
This has not yet led to full-scale uranium enrichment - a process that creates fuel for nuclear reactors and, potentially, for a nuclear bomb - but Western powers are concerned.