"The negotiations have been positive and progressive, and in Geneva the seven nations got a better understanding of one another views," Jalili was quoted as saying by the Mehr news agency.

He was referring to his talks on July 19 with representatives of major powers including EU foreign policy chief Javier Solana and, for the first time, an official from Tehran's arch-foe the United States, William Burns.

In Geneva, Iran was set a two-week deadline which expires on to give a final answer to world powers who have offered a package of incentives to try to persuade Tehran to halt sensitive nuclear work.

But Iran has rejected any deadline, saying it was agreed in Geneva that it would during a two week period examine the proposal put forward by permanent UN Security Council members Britain, China, France, Russia and the United States plus Germany.

The six nations, concerned that Tehran is pursuing a clandestine nuclear weapons project, have offered to start pre-negotiations during which time Tehran would face no further sanctions if it did not add any more uranium-enriching centrifuges.

The package, offered to Iran in June, includes trade incentives and help with a civilian nuclear programme in return for suspending enrichment.

Iran is under three sets of UN Security Council sanctions over its refusal to halt uranium enrichment, a process which makes nuclear fuel but can also create the fissile core of an atomic bomb.

Iranian President Mahmoud Ahmadinejad said in an interview with US television on Monday that if the United States adopted a genuinely new approach to his country Tehran would respond in a positive way.

He also denied that Iran was working to manufacture a nuclear bomb.

The interview followed Ahmadinejad's announcement on Saturday that Iran had boosted the number of uranium-enriching centrifuges to 6,000, in an expansion of its nuclear drive that defies the international calls for a freeze.

Israeli Defence Minister Ehud Barak, whose country considers Iran its greatest threat, urged the United States during a visit to Washington to keep all options open in dealing with Iran's nuclear programme.

"A policy that consists of keeping all options on the table must be maintained," Barak told US Defence Secretary Robert Gates, his ministry said on Tuesday.

"Iran's plans pose a threat to regional and global stability. We insist that it is vital to continue tightening the economic and financial sanctions imposed on the Iranians."

Israel is widely believed to be the only nuclear armed state in the Middle East although it has a policy of neither confirming or denying it has a nuclear arsenal and does not allow international inspections.

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