However, mindful of the situation in Iraq, Congressmen warned that nothing in the document should be "construed as authorising the use of force against Iran".

Although it does not name any country, the measure is seen as a clear warning to Russia and China, two key members of the UN Security Council who have been resisting calls for new international sanctions against Tehran in response to its refusal to halt uranium enrichment.

Russia has been involved in an $800 million project to help Iran build a nuclear power plant in Bushehr and has been selling it weapons, while China has been accused of supplying it with advanced missile technology.

The bill was passed by the senate on Saturday after clearing the House of Representatives a day earlier. It came as Iran and the EU are engaged in delicate negotiations designed to persuade the former to halt its enrichment work and avoid a major international showdown.

Bill Frist, the US senate majority leader, said: "Enactment of this legislation ensures that ILSA [the Iran and Libya Sanctions Act] will continue to impede Iran's efforts to acquire nuclear weapons.  

"This act also provides important new authority for the administration to block financial transactions related to Iran's weapons of mass destruction programmes, and encourages the administration to use all available leverage over Russia to gain Russian support for multilateral sanctions against Iran."

Reactions

Senator Norm Coleman said: "For the sake of our national security, the US must ensure that the sensitive nuclear technology that we share with partner countries does not fall into the hands of the Iranians. 

"Aiding Iran to become a nuclear power, even inadvertently, is unacceptable"

Senator Norm Coleman

"The Iranians have demonstrated that they are deceitful, obstructionist and bent on destroying Israel and all of Western civilization. We know where this path is going to lead. Aiding Iran to become a nuclear power, even inadvertently, is unacceptable."

Ileana Ros-Lehtinen, a Republican Representative and a sponsor of the bill, hailed its passage by saying that it would deny Iran "the technical assistance, financial resources and political legitimacy to develop nuclear weapons and support terrorism".

Tom Lantos, the top Democrat on the House International Affairs Committee, argued that the world should use every peaceful means possible "to defeat Iran's reckless nuclear military ambitions".