The Iraqi government has been accused of denying Iranian dissidents living in Camp Ashraf free access to medical treatment.
The National Council of Resistance of Iran claims that officials prevented a woman who has thyroid cancer from going to hospital in Baghdad.
The group says another resident of the camp was prevented from going with her as a nurse and translator.
More than 3,000 people live in Camp Ashraf, north of Baghdad.
Those at the camp, which was previously under the control of US forces, are members of an exiled Iranian opposition group, the People's Mujahideen of Iran (PMOI).
The National Council of Resistance of Iran said that the woman, Elham Fardipour, would have had to travel to Baghdad with the same Iraqi soldiers who had in the past taken part in attacks on the camp.
It said "in these circumstances, she was compelled to cancel her appointment".
The group also called on the United Nations and the American government to end what it alleges has been "the nearly two-year-long inhumane siege of Ashraf".
The group has accused Iraq of "numerous cases" of denying treatment to terminally ill patients, and claims that their suffering has been increased by the government's "psychological warfare" against the camp's residents, including the chanting of slogans against Iranian resistance groups from 120 loudspeakers positioned around the camp.
The People's Mujahedin Organisation of Iran, a leftist group, launched attacks not just on the clerical leaders of Iran but on their predecessor, the Shah.
In the 1980s, they were accused of a bombing campaign against new Islamist leadership. The most devastating attack, in 1981, killed some 70 senior officials, including the Chief Justice Mohammed Beheshti and a number of MPs and members of the cabinet.