Fresh talks with European negotiators on Iran's controversial nuclear programme have ended without agreement but are set to resume shortly.
Iran denies claims it wants to build nuclear weapons
An Iranian envoy said after meeting officials from the UK, France and Germany in Vienna that Iran still hoped to reach a compromise.
The EU nations are offering Iran civil nuclear technology if it agrees to abandon uranium enrichment.
Iran denies that it is seeking to acquire a nuclear arsenal.
An unnamed UK Foreign Office spokesman told Reuters news agency "some progress" had been made and new talks would follow shortly.
Sirus Naseri, a member of the Iranian delegation, confirmed the next meeting would be "soon".
"We're negotiating, we're trying to come to an agreement," he added.
In Tehran, Iran's Supreme leader Ayatollah Ali Khamenei
warned that his country would abandon the talks if the European
countries made "illogical demands".
"Wherever there has been a logical discussion... we have
accepted it. And wherever there is coercion, we have
resisted and will resist," state-run television quoted him as saying.
'No new offer'
Diplomats had warned that the talks could be the final chance for agreement before a crucial meeting on 25 November of the UN's nuclear watchdog, the International Atomic Energy Agency.
The Vienna-based body, which was not directly involved in the latest talks, has the power to refer the Iranian issue to the UN Security Council, which may choose to impose sanctions.
Despite possessing huge oil and gas reserves, the Iranian government insists its nuclear programme is for peaceful purposes.
However, enriched uranium can be used for weapons as well as fuel.
Earlier, a senior official in Tehran warned it could take months to agree to the EU request to suspend uranium enrichment.
National security delegate Hossein Mousavian said: "We will not have any new offer at Wednesday's meeting but ... we will discuss the European proposal's ambiguities."
Iran says it has co-operated with the IAEA and has developed its nuclear technology under international safeguards and standards.