Iran on Sunday sent a veiled warning to Britain, France and Germany after they strongly criticized Tehran for starting up a uranium conversion plant, IRNA reported from Tehran.

Foreign Ministry spokesman Hamid Reza Asefi told reporters here that 'any plan outside the agreement between us and these three European countries could destroy the process of confidence-building'.

The official also called on the three European heavyweights to honor their commitments to the nuclear Non-Proliferation Treaty (NPT) as well as Tehran Declaration which they signed last year.

Asefi stressed that Iran's resumption of work on a first part of the nuclear fuel cycle, doing uranium conversion at a processing plant in Isfahan, did not violate its commitments.

Tehran announced in October its voluntary suspension of uranium enrichment activities as a goodwill gesture as well as signed an additional protocol to NPT for snap inspections of its nuclear facilities.

Asked in a weekly news briefing to comment on the criticism voiced by Britain, Germany and France about the resumption of work on the nuclear fuel cycle in the Isfahan installation, Asefi said, "What has been announced does not violate our commitments."

"The Islamic Republic invites the three European countries to remain tied to their commitments within the framework of NPT and Tehran Declaration," he added.

The International Atomic Energy Agency (IAEA) has confirmed that Iran had announced in advance its intention to reopen the plant, while conceding there was nothing controversial about it.

Asefi denounced what it called 'inexpert and baseless' reports on Iran's nuclear operations, notably the one by Reuters news agency which has claimed the discovery of new bomb-grade uranium traces in Iran.

"The International Atomic Energy Agency experts have not reported any case to this effect at the end of their recent visit to Tehran," he said.

Reuters had quoted an unnamed Western diplomat as saying that the UN atomic watchdog had found traces of highly-enriched uranium at sites, allegedly not known to the IAEA in the past.

Asefi said, "There is no center which we may have hidden and we have not spared any cooperation with the International Atomic Energy Agency."

Iran has already denied being involved in weapons-grade uranium enrichment, clarifying that traces of the nuclear material found by the UN inspectors last year were related to the contaminated equipment bought from abroad.

Asefi stressed that 'the Islamic Republic is committed to what it has announced so far and believes that various issues will be resolved through the agreement of the two sides'.

Asefi also described a visit by the IAEA director general, Mohamed ElBaradei, to Iran on Tuesday as 'very important'.

"Various issues, including the resolution of remaining problems, will be on the agenda during Mr. Elbaradei's visit," he said adding the visit would be shortly taken up by a team of IAEA inspectors.

Meanwhile, Asefi denounced sanctions imposed by the United States on 13 foreign companies in seven countries because of allegedly selling equipment and technology to Iran, which Washington claims could be used in weapons programs.

State Department spokesman, Adam Ereli, said on Friday that the sanctions, to be in effect until March 31, 2006, included five Chinese companies, two in Macedonia, two in Russia and one each in North Korea, Taiwan, Belarus and the United Arab Emirates.

Asefi said, "The American government has shown that it does not spare any opportunity to impose its policies (on others) and the fact that the global community has been resisting such policies and pursuing an independent policy is indicative of its opposition to this move."

The United States accuses that Iran's peaceful nuclear activities are a cover to build atomic bombs.

Tehran says its nuclear program is in accordance with the country's bid to produce 7,000 megawatts of electricity in the next 20 years, when the country's oil and gas reserves become overstretched.