Iran's top nuclear negotiator on Friday welcomed the return of leading world powers to talks over the country's disputed atomic programme, but urged them "not to repeat their past mistakes".

Talks stalled in June when Iran rejected a proposal to suspend part of its nuclear programme, asking for more substantial relief from sanctions.

Saeed Jalili, the secretary of Iran's Supreme National Security Council, said Friday that Iran had invited world powers to resolve the impasse six months ago, which had now been considered.

"There was a six-month delay but they recently announced they are ready to come back for talks," he told journalists at the Iranian embassy during a trip to New Delhi.

"We welcome their return to the talks. We hope that they will come to the talks with a constructive approach and (that) they will not repeat their past mistakes," he added, without elaborating.

The last round of talks between Iran and the so-called P5+1 powers -- the United States, Russia, China, France, Germany and Britain -- yielded no breakthrough in Moscow in June.

In late November the six powers engaging Iran over its nuclear programme said they were willing to hold a new round of negotiations with Tehran.

Western powers accuse Iran of seeking to acquire a weapons capability under the guise of its nuclear energy programme. Iran denies the charge, saying its work is for peaceful purposes only.