Ahmadinejad looks set to announce the first stage of 'industrial-scale' uranium enrichment.
Iran's president may announce on Monday his country has begun the first stage of what it calls "industrial-scale" uranium enrichment, a move likely to anger the West which fears Tehran aims to build atomic bombs.
President Mahmoud Ahmadinejad will reveal what Iranian media and officials have described as the "good news" during a tour of the enrichment facility at Natanz, a desert site in central Iran that is surrounded by a high fence and anti-aircraft guns.
Iranian newspapers suggested his declaration would involve saying Iran had installed new centrifuges used in the enrichment process, which can make power-plant fuel or material for warheads. But officials have been tight-lipped on details.
"Good atomic news will be announced today in the afternoon by the president in Natanz," Mohammad Saeedi, deputy head of Iran's Atomic Energy Organisation, was quoted by Iran's ISNA news agency as saying.
Ahmadinejad arrived to tour the site at Natanz, about 200 km (125 miles) south of Tehran, ahead of a news conference expected at about 1200 GMT.
Tehran has rejected U.N. demands to halt enrichment and has vowed to expand what it says is peaceful atomic work. The U.N. Security Council has passed two sanctions resolutions on Iran since December after talks to end the row collapsed last year.
Iran says it is open to talks to defuse the row.
"We are ready to negotiate and reach an agreement with Western countries in order to remove their worries about nuclear Iran without putting an end to our scientific development," Iran's chief nuclear negotiator, Ali Larijani, said on Monday.
He said U.N. resolutions would not help and creating such tension would provoke a "serious reaction" from Iran, Mehr News Agency reported from a speech he gave in Mashhad, eastern Iran.
Iran, which according to diplomats has set up almost 1,000 centrifuges at Natanz, has said it plans to install 3,000 there as the first stage towards "industrial-scale" nuclear fuel production.
Iran has so far only produced tiny quantities of enriched uranium in tests. Eventually, it aims to operate about 54,000 centrifuges.
"Some sources say that Iran wants to announce the start-up of 18 cascades as good news," the daily Etemad-e Melli said.
The centrifuges are installed in cascades or networks of 164 machines each, so 18 cascades is equivalent to almost 3,000. The paper described the move as "semi-industrial scale" operations.
With 3,000 machines, Iran could make enough material for a bomb in one year, if it wanted, Western experts say.
Iran, the world's fourth largest oil exporter, says it wants to make fuel for a network of nuclear power plants its plans to build so it can preserve its oil and gas reserves for exports. Its first atomic plant is still under construction.
The International Atomic Energy Agency (IAEA), the U.N.'s nuclear watchdog, says it has gaps in its knowledge about Iran's plans that must be filled before it can say they are peaceful.
The IAEA is pushing Tehran to agree to let it install cameras in the underground section of Natanz to monitor Iran's work. Iran says such intrusive surveillance goes beyond its basic safeguards commitment to the IAEA. Talks continue.