Time is running out for Iran to avoid UN sanctions over its nuclear policy, Europe's foreign policy chief says.
The UN Security Council has told Tehran to suspend enrichment, amid fears it is trying to build nuclear arms.
The EU's Javier Solana told the European Parliament that Iran had not done so, and must now decide if the time for talks "has come to an end."
Iran's President Mahmoud Ahmadinejad has ruled out ending enrichment and says its programme is for civilian use.
Mr Solana has had a number of meetings with Iran's top nuclear negotiator since Tehran refused a 31 August deadline from the UN to halt enrichment.
The US and key EU powers now say they will seek a fresh UN resolution imposing sanctions.
Mr Solana told parliament: "This dialogue I am maintaining cannot last forever.
"It is up to the Iranians now to decide whether this time has come to an end."