"Today's breaking of seals is yet another sign of Iran's disregard for international concerns," Matt Boland, spokesman for the US mission to international organizations in Vienna, told AFP.

Iran on Monday took the first steps to break a suspension of nuclear fuel cycle work, which it had begun in November to start talks with the European Union on getting trade and other benefits in return for guarantees it was not making atomic weapons.

Iranian technicians on Wednesday removed seals placed by the UN watchdog International Atomic Energy Agency (IAEA) at a uranium conversion plant in Isfahan, 400 kilometres (250 miles) south of Tehran, allowing the facility to return to full capacity and raising the stakes in a standoff with the international community.

The United States accuses Tehran of covertly developing nuclear weapons, a charge vehemently denied by Iran which says its atomic program is a peaceful effort to generate electricity.

Boland said the United States "strongly" supports the European Union's effort through talks with Tehran "to convince Iran to stop its dangerous activities."

"We urge Iran to give serious consideration to the EU's proposals," for the Islamic Republic to suspend all nuclear fuel cycle work in order to guarantee it will not make atomic weapons, Boland said.

Iran's removal of the seals comes as the European Union tries to win approval at a emergency IAEA meeting in Vienna for a draft resolution calling on Iran to reverse its decision to push ahead with the nuclear fuel work.

Conversion turns uranium ore or yellowcake into a feed gas for making enriched uranium, which can be the fuel for reactors or the explosive core of atomic bombs.

Iran points out that its right to the nuclear fuel cycle is legally enshrined under the nuclear Non-Proliferation Treaty and that it has infringed no international rules by resuming uranium conversion.

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