European Union foreign policy chief Javier Solana held "positive" talks Friday with Iran's nuclear negotiator and expects elements of Tehran's response to an international offer very soon, his spokeswoman said.
"They had a positive, constructive conversation. They agreed to remain in contact" during telephone talks, said Solana's spokeswoman, Cristina Gallach.
She said Iran's top nuclear negotiator Saeed Jalili announced he would send a response "very soon" to an international package of incentives aimed at persuading Tehran to suspend nuclear enrichment activities.
It would contain "more concrete elements", she said.
Earlier, Iran's Mehr news agency said the Islamic republic's ambassador had delivered its answer to a letter outlining the proposals by world powers.
Solana was in London Friday and Gallach declined to say whether he would be likely to see the offer the same day.
In an effort to persuade Iran to suspend uranium enrichment, permanent Security Council members the U.K., China, France, Russia and the U.S. plus Germany have re-worked an offer originally made in 2006. It proposes a series of technological and other incentives in exchange for Tehran's suspension of enrichment operations.
Solana has been battling to establish high-level talks aimed at getting Iran to accept the package, but the Islamic republic refuses to suspend enrichment as a precondition for negotiating.
Iran insists it has the right to enrich uranium to make nuclear fuel to help meet its electricity needs and has so far defied Security Council resolutions which demand it halt the process.
At highly refined levels, such work can also make the fissile core of an atomic bomb but Iran insists its nuclear program is peaceful.