"It has been a long, constructive negotiation," Larijani told reporters at the end of two days of meetings in the German capital.

"We have been able to arrive at some positive conclusions.

"Today we have discussed modalities with the aim of coming back to the main negotiations as soon as possible."

In a businesslike press conference, Solana told reporters: "We have been progressing. We will have a new contact in the middle of next week."

Sources close to the talks said the contact could take place over the phone and did not necessarily mean they would be meeting face to face.

Larijani was to hold talks with German Foreign Minister Frank-Walter Steinmeier later on Thursday at the request of Solana.

The talks in Berlin were the first time Solana and Larijani had met for more than two weeks.

During that time European diplomats have tried to ratchet up the pressure by warning that time is running out for Iran to agree to UN Security Council demands to suspend uranium enrichment activities and thus avert possible United Nations sanctions.

Iran defied the Security Council's August 31 deadline for it to stop uranium enrichment, which makes fuel for civilian nuclear power reactors but also, in highly refined form, the raw material for atomic weapons.

Iran insists its enrichment work is solely for peaceful purposes.

Although European powers have expressed some hope for a breakthrough, Iranian President Mahmoud Ahmadinejad remained defiant Wednesday in the face of Western pressure.