Iran is set to meet six world powers in the Swiss city of Geneva to discuss its nuclear programme.They are the first talks in more than a year, but analysts say any breakthrough is unlikely.
On Sunday Iran announced that it had delivered its first domestically produced raw uranium to a plant that can make it ready for enrichment.
The US criticised the move but Tehran said it would now go to the talks with "strength and power".
On state television, nuclear chief Ali Akbar Salehi said the Geneva talks were for the benefit of the other countries, not Iran.
"We want to create a graceful solution out of the political deadlock for those who have pressurised us," he said.
The US and its allies believe Iran may be trying to produce nuclear weapons but Tehran says its nuclear programme is for peaceful civilian purposes.
Iran's top nuclear negotiator Saeed Jalili will meet EU foreign affairs chief Catherine Ashton and senior officials from the five permanent members of the UN Security Council - the US, Russia, China, France and Britain - plus Germany.
The talks are scheduled to last for two days. But analysts say the best outcome that can be hoped for is simply the agreement of further meetings.
The UN Security Council has said that until Iran's peaceful intentions can be fully established, it should stop enrichment and other nuclear activities.
Iran is under four sets of UN sanctions over its refusal to heed repeated Security Council ultimatums to suspend uranium enrichment.
The latest UN sanctions, adopted on 9 June, include a ban on dealing with Iranian banks and insurance companies, as well as steps to prevent investment in Tehran's oil and gas sector.
Iran says that as a signatory of the Nuclear Non-Proliferation Treaty, it has the right to enrich uranium for fuel for civil nuclear power.
Yellowcake stocks
On Sunday, Iran said it had mined and produced its first home-manufactured uranium yellowcake.
Mr Salehi said: "The West had counted on the possibility of us being in trouble over raw material but today we had the first batch of yellowcake [raw uranium] from Gachin mine sent to Isfahan [conversion] facility."
Enriched uranium can be used for fuel in reactors or made into nuclear bombs.
Iran was believed to be running low on its stock of yellowcake, originally imported from South Africa in the 1970s.
Producing it domestically would enable Iran to circumvent four rounds of increasingly harsh UN sanctions aimed at forcing it to comply with UN Security Council resolutions and freeze uranium enrichment.
White House National Security Council spokesman Mike Hammer said the announcement was not unexpected, as Iran had been trying to develop its own uranium programme for years.
"However... this calls into further question Iran's intentions and raises additional concerns at a time when Iran needs to address the concerns of the international community," Mr Hammer said.
