The U.S. Treasury Department has announced sanctions against Tejarat Bank, the third largest bank in Iran and the largest private bank in the Middle Eastern country.

David Cohen, the U.S. Treasury's Under Secretary for Terrorism and Financial Intelligence, said in a statement that the action against Bank Tejarat strikes at one of Iran's few remaining access points to the international financial system.

He said the sanction is to weaken Tehran's financial capacity in developing its nuclear program.

Bank Tejarat is suspected of supplying funds for the purchase of uranium and the development of weapons of mass destruction.

The Treasury's move comes right on the heels of the European Union's announcement to ban Iranian crude oil imports.

The U.S. has now sanctioned 23 financial institutions linked to Iran.