The U.S. is concerned about a six-week stall in residents leaving a camp near Iraq's Iranian border long used as a paramilitary camp by anti-regime Iranians.

The Obama administration has made the residents' departure from Camp Ashraf a condition for the Mujahadin-e-Khalq to be removed from a U.S. terrorism list.

Some 2,000 MEK members have left the Iraqi camp this year, but none since May 5. About 1,200 remain.

State Department spokeswoman Victoria Nuland urged the MEK to cooperate with Iraqi and U.N. officials, calling the camp's closure a "key factor in determining whether the organization remains invested in its violent past."

The MEK says it renounced violence last decade.

Secretary of State Hillary Rodham Clinton must decide by Oct. 1 whether the MEK leaves the terrorism list.