Federal prosecutors continued legal action on Friday to seize properties, including several mosques, owned by a non-profit Muslim organization with alleged ties to the Iranian government.
Federal Marshals delivered notices initiating possible seizure proceedings against the Islamic Education Center in Potomac, Maryland just outside Washington.
Authorities are moving against properties linked to the New York based Alavi Foundation.
Prosecutors accuse the foundation of funneling millions of dollars to Iran's state-owned Bank Melli through a front company called the Assa Corporation.
The U.S. Treasury accuses the bank of supporting Iran's nuclear program and has banned U.S. citizens from doing business with the financial institution.
A Muslin rights group, the Council on American-Islamic Relations, criticized the move to seize the mosques.
The group's communications director is Ibrahim Hooper.
"What we are really concerned about is the U.S. government seizing houses of worship," said Ibrahim Hooper. "Whether it is a mosque, a synagogue, a church, I think it sends a very chilling message in terms of freedom of religion to people of all faiths and it is something that all Americans should be concerned about."
A spokeswoman for the U.S. Attorney's Office in New York made it clear there are no allegations of wrongdoing and no action taken against tenants or occupants of the properties.
In addition to the mosque in Maryland, court documents say the Alavi Foundation also owns mosques in Queens, New York, Carmichael, California and the Islamic Education Center of Greater Houston in Texas.
Faheem Kazimi is chairman of the board of the Houston organization.
"I want to make it very clear to people that the Islamic Education Center of Houston is a non-profit organization," said Faheem Kazimi. "It is an independent organization not affiliated with any of these other organizations."
A New York skyscraper involved in the case is known as the Piaget building. A report by the Associated Press says the structure is worth more than $500 million.
An attorney for Alavi says the foundation has been cooperating with the U.S. government and is disappointed with the lawsuit.
He says the foundation will dispute the government's claims in court.
On Thursday U.S. President Barack Obama renewed long-standing sanctions against Iran for another year, saying relations with Tehran have not yet returned to normal.
The United States and Iran have had no diplomatic ties since the hostage crisis that followed the 1979 Islamic Revolution and the storming of the U.S. Embassy in Tehran.