A new round of talks between Iran and world powers over Tehran's nuclear programme will make or break the negotiations, a senior Iranian official said on Friday.
In a shift of policy, Washington is sending for the first time senior U.S. diplomat William Burns to join European Union foreign policy chief Javier Solana and officials from Britain, France, Germany, Russia and China for talks with Iran's chief nuclear negotiator Saeed Jalili on Saturday.
"These talks will clarify the fate of the negotiations. After the meeting, either negotiations will continue or it will fully stop," the Iranian official told Reuters.
When asked whether it meant Iran was ready to freeze any expansion of its nuclear programme in return for the U.N. Security Council halting further sanctions measures, the source said "not at all".
The senior Iranian official said Jalili has a full mandate from the country's Supreme Leader Ayatollah Ali Khamenei and President Mahmoud Ahmadinejad to take any decision in the talks which he described as "crucial".
The powers are seeking a more detailed Iranian response to their enhanced offer of financial and diplomatic incentives to halt secretive nuclear activity that could yield atom bombs.
Iran has so far rejected to halt the sensitive work, describing it as a "red line" for the Islamic Republic.
The world's fourth-largest oil-producer says the aim of its nuclear programme is solely to generate electricity so that it can export more crude and gas.
Tensions with Iran have intensified, particularly since Tehran tested missiles last week, alarming Israel and pushing up oil prices. Washington responded to the tests by saying it would defend its allies against any possible attacks.
Solana said he hoped for a "constructive response" at his meeting with Jalili but that he could not guarantee success.
