The US government on Wednesday launched steps to seize a 36-storey New York office tower allegedly part-owned by the Iranian government in violation of sanctions against Tehran.

US authorities said the building, located on Manhattan's prestigious Fifth Avenue, was partly controlled by an Iranian government bank through a front company based in the UK's Channel Islands.

The State Department said Iran's interest in the building breached US financial sanctions against Tehran aimed at thwarting the regime's alleged pursuit of nuclear weapons.

The US justice department filed a civil complaint seeking the forfeiture of a 40 per cent stake in the building owned by Assa Corporation, an alleged front company for Iran's Bank Melli.

The US and European Union have both imposed sanctions against Bank Melli over the past year, while the United Nations has called for countries to exercise "scrutiny" over its activities.

In a statement justifying the seizure on Wednesday, the state department said the bank provided "financial services, including opening letters of credit and maintaining accounts, for Iranian front companies and entities engaged in proliferation activities".

The move signals one of the most visible steps to date in US efforts to ratchet up pressure on Iran, particularly in the financial sector,amid an impasse in international talks over fresh measures against Tehran.

Iran has pressed ahead with its nuclear programme despite a series of United Nations resolution, while leading experts have warned it is coming closer to nuclear weapon capability. Iran maintains its nuclear programme is purely peaceful.

President-elect Barack Obama has said he intends to develop both "carrots" and "sticks" to persuade Tehran to rein in its nuclear programme, in remarks highlighting the likelihood that his administration will continue the sanctions effort.

The state department said the building, located at 650 Fifth Avenue, was co-owned by Assa Corporation and Alavi Foundation of New York, a non-profit Iranian charitable organisation.

The tower was constructed about 30 years ago by the Pahlavi Foundation, a nonprofit group set up by the late Shah Mohammed Reza Pahlavi, according to the US justice department. The Shah, a US ally,was overthrown as the Iranian leader in 1979.

The organisation changed names to Bonyad Mostazafan after the 1979 revolution and then changed names again to the Alavi Foundation.