Iran has said it will not be possible by tomorrow’s deadline to reach a comprehensive deal with world powers aimed at resolving the stand-off over Tehran's nuclear ambitions, the Iranian Students News Agency ISNA reported today.
The United States, Britain, France, Germany, Russia and China began a final round of talks with Iran last Tuesday.
They were hoping to clinch a pact under which Tehran would curb its nuclear work in exchange for lifting economically crippling sanctions.
Iran rejects Western allegations that it has been seeking to develop a nuclear bomb capability.
Iranian and western diplomats close to the negotiations in Vienna told Reuters the two sides remained deadlocked.
They are deadlocked on the key issues of Iran's uranium enrichment capacity and the lifting of the sanctions.
The Iranian official was quoted as saying the sides "were trying to reach a framework accord on major issues like ...the number of centrifuges, enrichment capacity and the time frame of lifting sanctions."
Meanwhile, US Secretary of State John Kerry briefed Saudi Foreign Minister Saud al-Faisal and Israeli Prime Minister Benjamin Netanyahu on the negotiations.
Iran and Saudi Arabia, a close US ally which is worried about the implications of any rapprochement between Washington and Tehran, are regional rivals vying for influence in the Middle East.
Diplomatic sources said that Mr Kerry and Iranian Foreign Minister Mohammad Javad Zarif were discussing new ideas to unblock the negotiations between Tehran and the six powers.
Mr Kerry, Mr Zarif and European Union envoy Catherine Ashton met again yesterday.
Officials had said earlier in the week that deadlock remained on key issues, and that the deadline, already extended by four months along with a partial easing of sanctions, might need to be pushed back again.
Western officials say Iran is not budging on key issues such as uranium enrichment, an activity that can have both civilian and military uses.
They say Iran has refused to reduce its enrichment capacity, which Western officials say would leave it with the capacity to amass enough material for an atomic bomb in a few months.
Washington wants this "breakout" timeline extended to at least a year.
Another stumbling block is sanctions, which Iran wants ended swiftly and not, as the West wants, suspended and scrapped progressively as Iran fulfils the terms of a final deal.
Iran also objects to Western demands that such a deal should last up to 20 years.
However, diplomats say the six powers are likely to relent on demands for full disclosure of any secret weapon work by Tehran, in the interest of securing a deal.
