Iran announced on Sunday fresh talks with world powers on its nuclear drive and said it was open to a US offer for two-way discussions if Washington's intention was "authentic".

Iranian Foreign Minister Ali Akbar Salehi said the six world powers planned to resume talks in Kazakhstan on February 25 and he insisted Iran had never pulled back from the negotiations.

"I have good news, I've heard yesterday that 5+1 or EU3+3 will be meeting in Kazakhstan 25th of February," Salehi said during a panel discussion at the Munich Security Conference.

Iran and six world powers -- the US, China, Russia, Britain, France and Germany -- held three rounds of talks last year aimed at easing the standoff over Iran's nuclear activities, which Tehran insists are peaceful.

The six, known as the P5+1 or EU3+3, called on Iran to scale back its programme but stopped short of meeting Tehran's demands to scale back sanctions and the last round ended in stalemate in June in Moscow.

Since then, talks have been held up over disagreements on their location.

The new date for talks has not been confirmed by the office of the EU foreign policy chief, leading the negotiations.

"It was not us who has stepped back. But anyway we still are very hopeful," Salehi said.

He added that Iran took comments by US officials, including Vice President Joe Biden who said here Saturday Washington was ready to hold talks with Iran on its nuclear programme, "with positive consideration".

"We have no red line for negotiations, bilateral negotiations when it comes to negotiating over a particular subject," he said.

"If the subject is the nuclear file, yes we are ready for negotiation but we have to make sure... that the other side this time comes with authentic intention with a fair and real intention to resolve the issue," he said.

But he criticised as contradictory the desire for negotiation with Iran on the nuclear issue, while, on the other hand, the use of "threatening rhetorics that everything is on the table".

"If there is an honest intention on the other side, then we will take that into serious consideration," Salehi said.

Asked when direct US-Iranian negotiations would happen, Biden replied: "When the Iranian leadership, Supreme Leader, is serious."

"We have made it clear at the outset that... we would be prepared to meet bilaterally with the Iranian leadership," he said.

"That offer stands, but it must be real and tangible, and there has to be an agenda that they're prepared to speak to. We are not just prepared to do it for the exercise."

Israeli Prime Minister Benjamin Netanyahu, speaking just before the formal start of talks to build Israel's new ruling coalition, said the most important mission facing the new government was preventing a nuclear Iran.

"It is a mission which has become more complicated because Iran has equipped itself with new centrifuges which reduce the enrichment time," he said.

"We cannot live with this process."

It was the first official reaction since it emerged that Tehran was planning to install more modern equipment at the Natanz uranium enrichment plant in central Iran, according to a UN document seen by AFP in Vienna on Thursday.