World powers and Iran remain far apart despite two days of intensive talks over the Islamic republic’s nuclear programme, European Union foreign policy chief Catherine Ashton said after the negotiations ended today.

"Over two days of talks we had long and intensive discussions on the issues addressed in our confidence-building proposal," Ms Ashton said.

She was addressing a news conference in the Kazakh city of Almaty, where the negotiations took place.

"It became clear that our positions remain far apart," she said.

Negotiators had failed to narrow their differences when the two-day meeting began yesterday, which followed a round of talks in February, also in Almaty.

Iran responded yesterday to a limited offer to ease sanctions with a proposal of its own that puzzled western diplomats and which Russia said raised more questions than answers.

Iran's critics, which accuse it of seeking nuclear weapons capability, have accused the Islamic state in the past of using diplomacy as a stalling tactic.

The latest inconclusive talks are unlikely to reassure Israel, which says it could launch air strikes to stop Iran getting the bomb, if necessary.

Israel is widely believed to have the Middle East's only nuclear arsenal.

This morning, Ms Ashton held a bilateral meeting with her Iranian counterpart, an official involved in the talks said.

Chinese and French diplomats also met bilaterally with the Iranian delegation.

With a presidential election due in Iran in June, hopes for a breakthrough were slim even before the first day of talks.

Before the talks Iran declined to accept or reject an offer of modest sanctions relief in exchange for curbing its most sensitive nuclear work.

Iran's deputy negotiator Ali Bagheri said Iran had given a "detailed response to all the questions".

Russian Deputy Foreign Minister Sergei Ryabkov said: "Iran has given an answer to the proposals of the six powers."

He said: "It is the kind of answer that creates more questions ... But this shows that the negotiations are serious."

Without substantial progress in coming months, western governments are likely to impose new economic sanctions on Iran.