Iran has confirmed that it will not sign an additional protocol allowing the International Atomic Energy Agency greater and faster access to its nuclear sites.
By Sadeq Saba
BBC regional analyst
The statement is likely to cause concern within the European Union, which has been urging the Iranians to approve the protocol unconditionally.
Tehran needs to please the EU in order to get trade concessions and try to alleviate American pressures.
ElBaradei and the inspectors plan to visit a number of nuclear facilities
But the question of nuclear capability has become a key concern for Iran's leaders, and unites even the warring factions in the government.
Both the reformists and hardliners - who are at loggerheads over so many issues - are enthusiastic supporters of the country's nuclear programme.
It was the pro-reform President, Mohammad Khatami, who proudly announced on national television in February that Iran had become independent in producing fuel for its nuclear power station.
Iranian leaders from both factions hailed the surprise declaration as a huge achievement.
They say Iran's nuclear technology has been developed by its own scientists and they describe it as a source of power and pride for the nation.
During a recent parliamentary debate on Iran's nuclear programme, pro-reform MPs were more forceful than their hardline colleagues in insisting that Iran should not bow to external pressure and give up its nuclear capabilities.
Iran, of course, insists that its nuclear ambitions are entirely peaceful.
But for some Iranians, even those who are opposed to the Islamic government, nuclear arms are a legitimate national aspiration.
They say that the nuclear status of some of Iran's neighbours - such as Pakistan and its arch-enemy, Israel - means it has every right to make such weapons to boost the country's security and bargaining power.
Some circles in the Iranian Government may also believe that if the country possesses nuclear arms, the United States would not be able to exert such significant pressure on the Islamic government.