The United States is imposing new sanctions in an attempt to crack down on human rights abuses by Iran's security forces.

The U.S. State and Treasury departments announced the move Thursday, freezing assets of the Islamic Revolutionary Guard Corps, the Basij Resistance Force and the Law Enforcement Forces , also called Iran's national police.

The sanctions also bar U.S. citizens and other companies or institutions from dealing with the security forces.

Secretary of State Hillary Clinton accused the forces of taking part in the “ongoing brutal repression” of political dissidents, protesters and others following disputed presidential elections in 2009.

The United States and its allies, as well as the United Nations, have already hit Iran with several rounds of sanctions for pursuing nuclear weapons technology.

Late last year, the U.S. blacklisted 10 companies and five individuals accused of helping Tehran develop nuclear weapons.

The U.S. said they had links to either Bank Mellat or the Islamic Republic of Iran Shipping Lines, both of which were already under U.S. sanctions.

U.S. law prohibits Americans and U.S. businesses from doing business with sanctioned entities.

The United States and its Western allies allege Iran has long been using its nuclear program to make weapons. Iran says the program is for peaceful purposes.