Iraqi authorities are interrogating six members of an Iranian exile group who were arrested during deadly clashes with the Iraqi Army, police said on Monday.
Meanwhile, the US military said the Iraqi government had allowed entry to a medical assistance team after initially denying permission to enter Camp Ashraf, the rebel base 80 kilometres (50 miles) North of Baghdad.
"Six members of the People's Mujahedeen of Iran (PMOI) were arrested and are being questioned at the Khalis prison," the police official said.
The jail is about 20 kilometres (12.5 miles) South of Camp Ashraf, where members of the Iranian exile group clashed with Iraqi security forces on Friday.
The PMOI said that 33 people were killed and 300 wounded in the incident, but Iraqi security and hospital sources said three were killed.
The rebels say that Iraqi security forces were surrounding the camp, refusing access to journalists or humanitarian aid for the wounded.
The US military acknowledged it was initially denied access for medical assistance, but said late on Sunday a medical team had finally been allowed in to "provide any essential humanitarian medical assistance that may be required".
"The results of this medical assistance and our assessment of medical conditions is being provided to the Iraqi government, which will authorize any further assistance that may be required," the military said in a statement.
"As our entrance into the camp was purely for humanitarian purposes on behalf of the Iraqi Government, we will only provide the results of that visit to Iraqi officials," it added.
After the clashes, the United States said it was urging Iraqi officials "at the highest levels" to avoid violence and show restraint.
The PMOI used Camp Ashraf, which houses some 3,500 people, as a base for launching attacks on Iran during the rule of Iraqi dictator Saddam Hussein but US forces disarmed the group after the 2003 invasion of Iraq.
Since then the camp's residents have been protected under the Geneva conventions and were guarded by US troops, although Washington still officially considers the PMOI to be a terrorist organisation.
A left-wing Islamic movement, the PMOI was founded in 1965 in opposition to the Shah of Iran and has subsequently fought to oust the clerical regime that took power in Tehran after Iran's 1979 Islamic revolution.
Iran, which has jailed or executed many members of the outlawed organisation, hailed Iraq's actions on Saturday.