Iranian president Mohammad Khatami has said Iran is ready to reach an agreement over its nuclear programme.
Khatami's offer of possible compromise clashes with other signals from Tehran
Mr Khatami was speaking ahead of talks on Friday with European negotiators.
He said Tehran was ready to undertake not to pursue nuclear weapons - as long as Iran's right to have peaceful nuclear technology was recognised.
The EU has given Iran an ultimatum to freeze all uranium enrichment before a meeting of the International Atomic Energy Agency at the end of November.
If the ultimatum is not met, Iran will face being reported to the UN Security Council for possible sanctions.
Iran agreed in October last year to suspend the programme, but has since resumed the manufacture of centrifuges.
Centrifuges refine uranium, which can then be used in nuclear weapons.
Mr Khatami said Iran would continue negotiations and that he was optimistic they would yield a solution.
"Both sides have shown essential flexibility and I am not pessimistic," Mr Khatami said.
"Possible suspension will be voluntary. We do not accept any conditions," he said.
Iran insists that its nuclear programme is peaceful and it needs the energy. The United States alleges that Tehran has ambitions to build a nuclear bomb.
On Monday the head of the International Atomic Energy Agency Mohammed ElBaradei said Iran should suspend its uranium enrichment programme, and urged it to do so as a confidence building measure.
Signals from Iran on this issue are mixed though. On Sunday the Iranian parliament passed the first stage of a bill which would force the government to resume its uranium enrichment programme.
It received the endorsement of all 247 MPs present.