The European resolution, identical to the proposal by the UK, France and Germany on 10 September, states that Tehran should suspend all uranium enrichment-related activities and asks IAEA director-general Mohammed el-Baradei to submit a comprehensive report before November.

The US, on the other hand, asked that the draft include a 31 October deadline, a 'trigger mechanism' that would refer Iran to the UN Security Council. 'We want the resolution to lay out essential and urgent steps for Iran to take,' said a US official.

El-Baradei dismissed the idea of a deadline and repeated that his investigation had not established whether Iran was trying to develop nuclear weapons as Washington asserts. 'We haven't seen any concrete proof that there is a weapons programme,' he said. 'Can we say everything is peaceful? Obviously we are not at that stage.'

Tehran is seeking a swift end to the probe of its nuclear programme. It has hardened its stance, stressing it would not agree to an unlimited suspension of uranium enrichment. Hussain Mousavian, chief Iranian delegate to the IAEA meeting, warned that 'we will not accept any bargaining for an unlimited suspension'.

Amid the disagreements, the prospect of a final draft resolution being brought before the IAEA's 35-nation board of governors on 17 September was uncertain. Although a final draft may include US modifications, revelations of the rift are embarrassing. The possibility remains that the two camps will not be able to bridge their differences, and this could undermine the IAEA's work on Iran's nuclear dossier.