Iran wants to end the standoff with global powers over its nuclear programme swiftly but will not sacrifice its rights or interests for the sake of a solution, President Hassan Rouhani has said.

Meeting Russian President Vladimir Putin on the sidelines of a regional security summit on Friday, Rouhani said it was a good time for new steps to resolve the dispute over a programme Western states believe is aimed at developing nuclear weapons.

"Regarding the Iranian nuclear issue, we want the swiftest solution to it within international norms," Rouhani said at the meeting with Putin in Kyrgyzstan's capital, Bishkek.

I declare that only if there is political will, if there is mutual respect and mutual interest, and only if the rights of Iran's people are ensured, can we guarantee the peaceful character of Iran's nuclear programme. Hassan Rouhani, Iranian president

"Russia in the past has taken important steps in this sphere and now is the best opportunity for new steps from your side," said Rouhani, whose country has observer status in the Shanghai Cooperation Organisation, dominated by Russia and China.

The comments come two days after US ambassador Joseph MacManus to the UN nuclear watchdog, IAEA, said there had been "troubling developments" in Iran's nuclear programme.

Iran has been in on-off talks for years with six global powers seeking to ensure it does not develop nuclear weapons capability.

A solution has been elusive and the most recent talks, in April, ended without a breakthrough.

Iran said on Friday it has significantly reduced its stocks of 20-percent enriched uranium by converting it to reactor fuel.

The US and its allies demand Iran halt all enrichment, which Tehran rejects.

'Mutual respect'

Iran's nuclear chief Ali Akbar Salehi told state TV late on Thursday that stocks have fallen from 240 kilogrammes to around 140 kilogrammes as it is converted into fuel for a medical research reactor.

He said the remainder is also being converted.

An August report by the UN nuclear watchdog put Iran's stockpile of 20-percent enriched uranium at 185.5 kilogrammes.

Rouhani, who was elected in June, has said Iran will be more transparent and less confrontational in talks with the six powers - the US, Russia, China, Britain, France and Germany.

But he made clear earlier on Friday he was only ready to go so far, indicating Iran would not give up its right to enrich uranium.

"I declare that only if there is political will, if there is mutual respect and mutual interest, and only if the rights of Iran's people are ensured, can we guarantee the peaceful character of Iran's nuclear programme," he said.

Western diplomats say Iran has continued to expand its uranium enrichment capacity in recent months, potentially shortening the time it would need to produce sufficient highly-refined material for a bomb.

Rouhani said a date could be set for the next round of talks later this month during the UN General Assembly in New York, where meetings between Iran and some of the powers are expected.