THE United States said it would take part directly "from now on" in international talks with Iran over its nuclear activities, the latest move in the Obama Administration's promised diplomatic outreach to the Tehran Government.

"There&apos ;s nothing more important than trying to convince Iran to cease its efforts to obtain a nuclear weapon," the Secretary of State, Hillary Clinton, said. The United States would be a full participant with Britain, France, Germany, Russia and China in any future Iran negotiations, Mrs Clinton said.

The announcement, made in London after a meeting among the negotiating partners, broke with the Bush administration's policy of supporting talks between Iran and the others but not participating in them. Although President George Bush made an exception to the policy in July, allowing a senior US diplomat to attend a meeting at which Iran was present, his administration later said that Iran was not serious and that the effort would not be repeated.

A senior Administration official said there was no internal debate over whether to fully join the negotiations if and when another round is scheduled. "It was kind of silly that we had to walk out of the room" when the Iranians were present, the official said.

Iran offered no immediate public response to the announcement. Its official statements since President Obama offered in his inaugural speech to "extend a hand if you are willing to unclench your fist" have vacillated between hard-line and moderate. In comments on Wednesday before the London statement, the Iranian President, Mahmoud Ahmadinejad, said his country would welcome direct engagement with the United States, providing Mr Obama was "honest".

Mr Ahmadinejad also said he planned to announce "good nuclear news" to the nation yesterday. Reports suggest he will claim Iran has perfected techniques for the manufacture of uranium fuel.

David Albright, a former UN weapons inspector, said if that was all Mr Ahmadinejad claimed, there would be relief in the US Administration, which fears Iran could begin to use new centrifuges at its Natanz uranium enrichment plant, bringing it closer to a bomb-making capability.