The Bush administration moved Wednesday to clamp down financially on a New York City business suspected of acting as a front company for Iran''s Bank Melli, which has been accused of providing support to Iran''s nuclear program.

The Treasury Department''s action covers ASSA Corp. of New York City as well as its parent, ASSA Co. Ltd., located in the Channel Islands. Any assets belonging to the companies found in the United States are frozen and Americans are prohibited from doing business with them.

"This scheme to use a front company set up by Bank Melli — a known proliferator — to funnel money from the United States to Iran is yet another example of Iran''s duplicity," said Stuart Levey, the Treasury Department''s under secretary for terrorism and financial intelligence.

The U.S. government alleged that ASSA Corp. was created by Bank Melli to hold its interest in a building located at 650 Fifth Ave. in New York. The building''s construction had been partly financed by a Bank Melli loan, Treasury said. ASSA Corp. co-owns the 36-story building through a partnership formed with the Alavi Foundation of New York, called 650 Fifth Avenue Co., the government said.

The United States alleged that ASSA Corp. "has repeatedly transferred rental income generated from the 650 Fifth Avenue partnership back to Bank Melli through ASSA Co. Ltd." The government alleged that ASSA Corp. has shared financial and other information on a regular basis with Bank Melli.

The department said its action does not interfere with the business or other activities of the building''s tenants.

Last year the United States accused Bank Melli of providing services to Iran''s nuclear and ballistic missile programs and put the bank on its list of companies whose assets must be frozen.

The move announced Wednesday marks the latest effort to tighten the financial noose on Iran, which the United States accuses of bankrolling terrorism and seeking a nuclear bomb. The United States has already imposed sanctions on several state-run Iranian banks and businesses along with elements of its defense ministry and Revolutionary Guard Corps.

The Justice Department, meanwhile, filed a civil complaint in federal court seeking forfeiture of ASSA''s 40 percent interest in the New York building. The government alleged the company violated U.S. sanctions with Iran and engaged in money laundering.