Iran has requested last-minute talks with EU nations, three days before the UN's nuclear watchdog holds a key meeting on Tehran's nuclear programme.
Iranian negotiator Ali Larijani said Tehran wanted constructive talks
A UK Foreign Office spokesman said the UK, France and Germany, the so-called EU3, believed negotiations were at an end but would listen to Iran's views.
He said the EU3 countries had no new proposals of their own.
The UN's nuclear agency is due to meet on Monday to decide whether to report Iran to the UN Security Council.
The International Atomic Energy Agency's (IAEA) board of governors will study a report in which chief inspector Mohammed ElBaradei has said questions remain over Iran's nuclear programme.
Tehran insists its plans are peaceful.
The IAEA meeting could be followed by punitive measures by the UN Security Council.
Iranian chief nuclear negotiator Ali Larijani told Reuters news agency that discussions with the EU3, scheduled to take place in Vienna on Friday, were being held "to say we [Iran] are in favour of holding constructive negotiations".
The BBC's Emma Simpson in Moscow says the EU talks have been the only diplomatic door left open to Iran - and that although there has been no agreement, that door has now opened a little wider.
Meanwhile Iranian President Mahmoud Ahmadinejad, on a three-day visit to Malaysia, told a press conference Iran would continue its nuclear activities "under the supervision" of the IAEA.
Talk in Moscow on Wednesday on a Russian compromise proposal to enrich uranium on Russian territory for use in Iran's reactors failed to make a breakthrough.
Mr Larijani showed no signs of backing down on what he said was his country's "sovereign right" to pursue enrichment on its own territory.
An IAEA report earlier this week confirmed Iran was forging ahead with uranium enrichment, a first step in a process that can produce fuel for nuclear reactors or bomb material.
Tehran says its research is solely aimed at energy production, but Western powers are concerned that Iran's uranium enrichment programme is part of a plan to acquire nuclear weaponry.