Iran's declaration that it intended to accelerate its development of nuclear technology, in defiance of UN sanctions, was met with concern by the US and UK but Sergei Lavrov, the Russian foreign minister, said it was too early to draw conclusions on Iran's claims.
"We will follow the situation carefully on the basis of concrete facts and not on declarations that only worsen the situation," Lavrov told reporters.
The European Union, however, reiterated calls for Iran to suspend uranium enrichment.
The calmer response from Moscow is not wholly unexpected given that Russia is building Iran's first nuclear power station at Bushehr and has supplied the Islamic republic with sophisticated military equipment.
|Russia is helping Iran build its first |
nuclear power station at Bushehr [EPA]
However, Moscow has also supported two sets of UN sanctions aimed at persuading Iran to comply with demands to suspend enrichment of uranium.
Enrichment is the key issue in the standoff between Iran and the West as the process can produce nuclear fuel but in highly extended form can also make the fissile core for an atomic bomb.
In a grand ceremony at its Natanz uranium enrichment plant in central Iran on Monday, Ahmadinejad announced that the country was now able to enrich uranium on an industrial scale.
And on Tuesday the administration in Tehran made light of the criticism from the US and the UK.
"The objective of the Islamic Republic of Iran is not just the installation of 3,000 centrifuges at the Natanz plant but we are doing everything to install 50,000 centrifuges," Gholam Reza Aghazadeh, the head of the country's atomic energy programme, was quoted as saying by the state-run IRNA agency.
Meanwhile two UN nuclear inspectors began a trip to the Natanz facility.
The Fars news agency said the IAEA inspectors would stay in Iran for a week. An Iranian official confirmed the inspectors' arrival and said they were on a routine visit.
The inspectors' report, likely to emerge after their visit ends, could provide the first independent confirmation of whether Iran's enrichment is progressing as claimed.