Iran on Tuesday said it has formally agreed to resume talks on its controversial nuclear programme with six major powers which have been stalled since January.

Iran's official confirmation came in a letter delivered to the European Union foreign policy chief Catherine Ashton who spearheads the talks on behalf of the so-called P5+1 powers.

"We welcome your return to the negotiations based on cooperation on the common points," Iran's top nuclear negotiator Saeed Jalili was quoted as saying in the letter, according to a report by Iran's Arabic-language Al-Alam television.

It said the letter was handed over by Tehran's envoy to the EU.

In Brussels, Ashton's office confirmed receiving Jalili's response to a letter sent by Ashton in early February.

"We are studying it," a spokeswoman said, adding that Ashton "will respond in due course."

Jalili said in his letter that "the developments in recent months have shown that Iran's proposal package three years ago was based on the correct understanding of the realities."

He added that "respecting the nation's rights and refraining from pressure are the two main pillars of cooperation."

Ashton's letter, which followed unsuccessful January talks in Istanbul, reiterated the group's position on Iran's contentious nuclear issue.

Prior to Istanbul talks, Iran had participated in similar negotiations with the world powers in December 2010 in Geneva.

According to Ashton's spokesman, she also affirmed that the world powers were keen to continue talks with Iran without any preconditions.

Iran maintains that negotiations must revolve around its package given to world powers three years ago which does not specifically speak about its own atomic programme but insists rather on discussion about global nuclear disarmament and world security.

At the close of the Istanbul talks, Ashton told reporters that "it remains essential that Iran demonstrates that its nuclear programme is peaceful."

"We had hoped to embark on a discussion of practical ways forward, and have made every effort to make that happen. I am disappointed to say that this has not been possible," she said at that time.

On Monday, Iranian President Mahmoud Ahmadinejad had said in Istanbul that Tehran would respond "soon" to Ashton's letter.

"We welcome the wish of the 5+1 Group to return to the path of negotiations once again," he said, referring to the five permanent members of the UN Security Council plus Germany who are negotiating with Iran over its atomic programme.

"We have always been ready for talks, and we are ready today," he said.

Ahmadinejad added that the nuclear issue can be solved "in an hour-long meeting."

"If legal nuclear issues are brought up, well there is no need for 10 sessions, because regulations have cleared everything," he said. "Based on law, it is the Iranian nation's right to acquire the enrichment technology."

He added: "But the reality is that other policies under the guise of the nuclear issue are put on the table. It is clear that some Western governments do not want us to develop (in the nuclear field)."

World powers suspect Iran is masking a weapons drive under the pretext of a civilian nuclear programme. Tehran denies the charge.

Iran insists that being member of nuclear Non-Proliferation Treaty, it has the right to full nuclear technology, including enriching uranium, the most controversial part of its programme.

Iran's nuclear programme has already been the subject of six UN Security Council resolutions, four of which included a range of economic and political sanctions.

On top of those measures, the United States and the EU have imposed their own unilateral sanctions on the Islamic republic.