Six world powers wrapped up two days of "substantive" talks with Iran on its contentious nuclear programme here Tuesday, with the two sides agreeing to meet again in Istanbul next month.

Iranian President Mahmoud Ahmadinejad meanwhile called on the six -- Britain, China, France, Germany, Russia and the United States -- to lift international sanctions against his country if they want the talks to bear fruit.

Catherine Ashton, the European Union's top diplomat, described the Geneva talks as "detailed, substantive."

"We have had nearly two days of detailed, substantive talks focusing on the Iranian nuclear programme and the need for Iran to comply with international obligations," she said.

"The countries I represent are united in seeking a resolution of the international community's concerns regarding Iran's nuclear programme, which is the central purpose of these talks," she added.

"The talks will continue on the common points," Iran's chief negotiator Saeed Jalili told Iranian state television from Geneva after the meeting.

"Inshallah (God willing) based on the agreement reached (here) and that they stick to it we probably will meet in Istanbul in (the Iranian month of) Bahman (January 21 to February 20)," he added.

"We recognise Iran's rights, but insist it fulfils its obligations," said Ashton, who represented the five permanent powers of the Security Council -- Britain, China, France, Russia and the United States, plus Germany at the Geneva meeting.

A member of the Iranian delegation said the two sides would resume the bargaining in Istanbul at the end of January "to discuss cooperation and find common points."

Speaking in the central Iranian city of Arak, President Mahmoud Ahmadinejad pressed the six powers to lift sanctions imposed on his country over his failure to halt its uranium enrichment activities.

"If you come to the negotiations by cancelling all the nasty things and wrong decisions that you have adopted ... lift resolutions, sanctions and some restrictions that you have created ... then the talks will definitely be fruitful," he said in a speech broadcast on state television.

The two-day meeting here, after a 14-month break, is taking place amid tougher international sanctions on Tehran.

Iran is under four sets of UN sanctions over its refusal to suspend uranium enrichment, the sensitive process which can be used to make nuclear fuel or, in highly extended form, the fissile core of an atom bomb.

Iran rejects claims by the West and Israel that its uranium enrichment programme masks a covert bid to acquire nuclear weapons, maintaining that it is developing nuclear energy solely for peaceful purposes.

Prior to Tuesday's session, Western sources said the parties would attempt to hammer out an agenda for future discussions and described Monday's talks as "good, constructive, and in a good atmosphere."

"If the negotiations have carried on for such a long time, it was because there were things to talk about," said one source, who added that a number of subjects were addressed, "including the nuclear dossier."

Iran on Tuesday urged world powers to show "courage" and recognise the country's "right" to a nuclear fuel cycle, which includes enrichment.

"Acknowledging our nation's right to have the fuel cycle can be a start for great cooperation among different countries in peaceful nuclear activities," foreign ministry spokesman Ramin Mehmanparast said in Tehran.

And Jalili was quoted by Iran's Fars agency saying Tuesday that the "rights of Iran are non-negotiable."

"They can't be part of the subject of discussions. The Islamic Republic of Iran accepts these negotiations only in the spirit of cooperation... and refuses all pressure," he said.

Iran triggered heightened concern in the West on Sunday by revealing it had taken a new step in the nuclear fuel cycle, producing its first home-grown batch of the raw material for enrichment, uranium yellowcake and making it "self sufficient," according to the country's atomic chief.

Joining Ashton and Jalili at the Geneva talks were officials from Britain, China, France, Germany, Russia and the United States at the Swiss UN mission building.