Their criticism came after Iran's atomic energy chief Gholam Reza Aghazadeh said Sunday that work had resumed at the Isfahan installation in the centre of the country.

"This announcement sends the wrong signal about Iranian willingness to implement a suspension of nuclear enrichment-related activities," said a Foreign Office spokesman in London.

"It will make it more difficult for Iran to re-establish international confidence in her undertakings," he said, in a statement identical to ones issued in Paris and Berlin.

In a deal with the International Atomic Enegy Agency (IAEA) brokered by Britain, France and Germany last year, Tehran agreed to suspend uranium enrichment and related activities while UN inspectors delved into suspicions Iran was using atomic energy as a cover for developing nuclear weapons.

Iran, under massive international pressure to maintain the suspension, has consistently emphasised its right under the Non-Proliferation Treaty (NPT) to produce nuclear fuel for what it insists are strictly peaceful purposes.

"The uranium processing plant in Isfahan will produce all raw materials for the fuel cycle," Aghazadeh said on Sunday.

Britain, France and Germany have for the past seven months been working together in an effort to resolve international concerns about Iran's nuclear programme.

Foreign ministers from the three countries visited Tehran last October.

"Iran must explain her statement and her intentions," the Foreign Office statement said. "We reaffirm our firm support for the IAEA's ongoing work on this matter."

IAEA inspectors arrived in Iran on Saturday for a visit which Tehran had delayed earlier this month after the body condemned Iran for failing to report that it had designs for sophisticated P2 centrifuges for enriching uranium to levels that could be weapon-grade.

The IAEA has been investigating since February 2003 whether Iran's nuclear programme is peaceful, or devoted to secretly developing atomic weapons, as the United States alleges.

The body is to report its findings at a meeting in Vienna in June.

An IAEA ruling that Iran is in non-compliance with the NPT would send the issue to the UN Security Council, which could then impose sanctions on the Islamic republic.

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