The United States has condemned Iran for what Washington terms an "organized intimidation campaign."
The White House says Iran has arrested political leaders and activists, human rights defenders as well as student leaders, journalists and bloggers.
The White House also accused Tehran of denying its citizens access to information by jamming satellite transmissions and blocking Internet sites.
Analysts say Washington has been increasing pressure on Tehran as a wave of popular uprisings sweep northern Africa and the Middle East.
U.S. Sectetary of State Hillary Clinton on Feb. 23 praised the "bravery" of Iranian protesters and condemned the Iranian government for its systematic crackdown on dissent.
The White House statement came after an international advocacy group said two Iranian opposition leaders -- Mirhossein Mousavi and Mehdi Karoubi -- had been moved from their homes where they had been under virtual house arrest.
The International Campaign for Human Rights in Iran quoted an "informed source" as saying Mousavi and Karoubi, along with their wives, had been moved to a "'safe house' in an area close to Tehran".
The source said they had not been physically abused and that their new location was not a prison.
compiled from agency reports