In New York US prosecutors have taken steps to seize four US mosques and a Fifth Avenue skyscraper.
The building's owner is a non-profit Muslim organization. It was long-suspected of being secretly controlled by the Iranian government. Prosecutors filed a civil complaint in federal court on Thursday against the Alavi Foundation.
They are seeking the forfeiture of assets worth more than half a billion US dollars.
Prosecutors said the Alavi Foundation managed the office tower on behalf of the Iranian government, and had illegally funneled millions in rental income to Iran's state-owned Bank Melli.
The bank has been accused by a US Treasury official of providing support for Iran's nuclear program. The mosques and the skyscraper will remain open while the forfeiture case works its way through court.