Washington - The US government moved Wednesday to seize the assets of a New York firm accused of operating as a front for an Iranian bank already under sanctions.

The Treasury Department said ASSA Corp in New York and its parent company ASSA Co Ltd in the Channel Islands were working or controlled by Iranian state-run Bank Melli, which has allegedly provided financial support to Iran's nuclear activities.

ASSA served as the stakeholder in Bank Melli's interest in a building in Manhattan, the Treasury Department said. The action freezes the assets of the companies and prohibits Americans from doing business with them.

The announcement marks the latest moves to clamp down on Iran's financial system for the Islamic state's defiance of UN demands to halt uranium enrichment, a process that could lead to nuclear weapons.

Iran says its nuclear programme is solely for producing energy.

The Justice Department filed forfeiture claim to strip both ASSA firms of their control in the office tower.

The US government placed sanctions on Bank Melli in 2007 in addition to other Iranian financial firms. (dpa)