Last-minute talks between Iran and EU nations over Tehran's nuclear programme have broken up without agreement.
Western powers suspect Iran's nuclear ambitions are not peaceful
The discussions were called by Iran in a late bid to avoid possible UN action over its nuclear programme.
The International Atomic Energy Agency (IAEA), the UN's nuclear watchdog, will decide on Monday if action is needed.
Meanwhile, Iranian President Mahmoud Ahmadinejad has accused the IAEA of being politically motivated and influenced by Western powers.
At Friday's talks, officials from the UK, France and Germany - the so-called EU3 - said they were there to listen to Iran, but they presented no new plans of their own.
A letter from the EU3 to Iran's chief nuclear negotiator, Ali Larijani, warned Iran earlier this week that any progress would be dependent on Iran stepping up co-operation with UN inspectors.
After the meeting, German Foreign Minister Frank-Walter Steinmeier said talks "were carried out in a constructive atmosphere but finally we were unable to reach agreement."
The EU and much of the international community want Iran to suspend all nuclear enrichment work, fearing it could eventually lead to arms production. Iran insists its only aim is civilian use.
After the failure of Friday's talks, attention will now switch to Monday's IAEA meeting, which will make an assessment of the situation and decide if action should be recommended.
The IAEA voted in February to report Iran to the UN Security Council, but recommended a month's delay in any action to see what further information emerged in the watchdog's latest report.
Despite the smiles Friday's meeting made no breakthrough
The agency itself came under strong attack from Mr Ahmadinejad on Friday, as he accused it and other international organisations of being politically motivated in their actions and influenced by Western powers.
"Regrettably most international organisations have turned into political organisations and the influence of great powers prevents them from taking fair and legally sound decisions," he said on a visit to Malaysia.
In a bid to end the crisis, Russia has proposed that uranium enrichment be carried out on Russian soil on behalf of Iran.
That way, Iran could benefit from nuclear energy but without the technology which could also lead to nuclear weapon production.
Iran has not accepted the Russia's proposal.
Despite Friday's setback, a deal could still be reached before Monday, Russia's Foreign Minister Sergey Lavrov was quoted as saying by the Interfax news agency.
The Russian proposal has been seen by many as a last chance for Iran to compromise with the IAEA.