The US yesterday banned the political wing of the Iranian opposition group People's Mujahedeen, froze its assets and moved to close down its offices here, the State Department said.

The move, announced in a notice signed by Secretary of State Colin Powell that was published in the Federal Register, outlaws the National Council of Resistance, declaring it to be a terrorist organisation.

The designation also applies to the group's alias "the National Council of Resistance of Iran" and includes "its US representative office and all other offices worldwide," Powell said in the notice.

The People's Mujahadeen - also known as the Mujahedeen e Khalq (MEK) - has been on Washington's terrorism blacklist for some time, but its political wing has fought the designation in US courts.

Amid the uncertainty over its status, the National Council of Resistance has maintained offices in Washington and other US cities and has frequently held news conferences to denounce the Iranian government.

Yesterday's announcement is aimed at closing that legal loophole, paving the way for US authorities to shut down the group's offices, according to State Department officials.

The officials said agents from the US Treasury Department had placed notices announcing the move on the doors of the group's office at the National Press Building in Washington, just blocks from the White House.

In addition, the officials said suspected members of the group had been notified that their continued affiliation was now illegal.

"Any continued material support for the MEK or use of its facilities or property under any of its aliases and any unauthorised dealing in property in which the MEK has an interest is a violation of US law," one official said.

The US move against the People's Mujahadeen follows a similar crackdown on the group in France, where police raided their headquarters in a Paris suburb in June, arresting scores of people.

The group's leader, Maryam Rajavi, was one of more than 160 people initially detained in the raids and her arrest outraged her followers, with a spate of self-immolation protests across Europe that left two women dead.

Rajavi and 16 others who were then placed under investigation were granted conditional release in early July after two weeks in detention, although that does not preclude charges being brought against them.

The group - which is also designated a terrorist organization by the European Union and Iran - has denied all wrongdoing.

With a programme that blends left-wing and Islamic ideology, the People's Mujahedeen took part in the 1979 revolution in Iran, but the movement was suppressed in the years that followed and its members fled abroad.

Under the leadership of Rajavi's husband, Massoud, the military wing of the group took refuge in Iraq in 1986, from where it organised attacks inside Iran. – Sapa.