Talks between the EU and Iran over Tehran's nuclear programme have got off to a good start, an EU official says.
Iran says its nuclear programme is for peaceful purposes
Foreign policy chief Javier Solana's spokeswoman said the talks were the basis for a positive second meeting, scheduled to take place on Tuesday.
She said Iran would give the meeting a "substantial response" to an incentives package agreed by world powers in June.
Earlier the UN nuclear watchdog chief said the world was "impatient" at Iran's failure so far to respond.
Mohamed ElBaradei said the earlier Tehran gave an anwer on the offer, the better it would be for everyone. The package is aimed at persuading Iran to halt uranium enrichment.
Mr Solana's spokeswoman said he had stressed the benefit to Iran of accepting the package, in an informal dinner in Brussels late on Thursday with Iran's top nuclear negotiator, Ali Larijani.
Mr Solana put the proposal to Iran in June
"We want to create the conditions for the start of negotiations as soon as possible... I have always said we are not using the word 'deadlines'," Christina Gallach said, quoted by Reuters news agency.
No further details of the meeting were released.
Mr Larijani said his country was serious about continuing negotiations.
Formal talks had been due this week but Iran postponed the meeting, citing security concerns.
They will now be held on Tuesday in the presence of diplomats from the UK, US, France, Germany, Russia and China, the six countries which agreed the package of measures aimed at persuading Teheran to suspend nuclear enrichment.
'Playing for time'
In Washington, a State Department spokesman told reporters on Thursday: "It's high time that [Iran] provide an answer."
Sean McCormack said foreign ministers of the six powers would meet next Wednesday to discuss negative steps against Iran if it had not given a clear answer, Reuters reported.
Correspondents say Iran's announcement that it wanted to postpone the EU talks appeared to be linked to a visit to the European parliament by the leader of a controversial exiled Iranian opposition group.
The BBC's Pam O'Toole says the postponement has stoked suspicions in some Western countries that Iran, under threat of UN Security Council action if it rejects the package, is playing for time.
Thursday's dinner was the first face to face meeting between Mr Larijani and Mr Solana since early June, when Mr Solana presented Iran with the package of proposals.