Five people have been killed in a rocket attack on a camp housing Iranian exiles in central Iraq, officials say.
A UN spokeswoman confirmed there had been a number of deaths at Camp Hurriya, a former US military base near Baghdad used by members of the People's Mujahideen Organisation of Iran (PMOI).
The PMOI said six men and one woman had been killed and more than 50 other people wounded, some of them seriously.
It complained that it was being stopped from taking the wounded to hospital.
The accusation was denied by Iraqi officials, who said casualties had been evacuated to hospital immediately, according to the UN.
Investigation call The National Council of Resistance of Iran (NCRI), a political umbrella group dominated by the PMOI, said on its website that Camp Hurriya (Liberty) came under missile and mortar attack at 05:45 (02:45 GMT).
"Six residents including a woman have been slain and more than 50 were wounded. Some of the wounded are in serious condition and the number of slain might increase," the statement said.
The group said there had been "no assistance" from the Iraqi authorities, and that the generator at the camp's clinic had been damaged.
A spokeswoman for the UN mission in Iraq, Eliana Nabaa, told the AFP news agency that the attack had "led to a number of deaths and injuries among the residents" and also left several Iraqi policeman hurt.
UN special envoy Martin Kobler had asked the local authorities to "promptly conduct an investigation into this", she added.
A police source in Baghdad told the BBC that five people had been killed.
Later, an interior ministry official said the rockets were thought to have been fired from an area west of the capital where the Badr Brigade operated.
The Badr Brigade is the military wing of the Badr Organisation, a Shia group which is close to the Iranian government, reports the BBC's Nahed Abouzeid in Baghdad.
About 3,000 members of the PMOI, also known as Mujahideen-e Khalq, were moved to Camp Hurriya last year on the insistence of the Iraqi government, which wanted to close the group's long-time base, Camp Ashraf. It is meant to be a temporary home while the UN resettles them.
Sharing the goal of removing the Shah of Iran with Ayatollah Ruhollah Khomeini, the PMOI took part in the 1979 Islamic Revolution. But the group, with its blend of Marxism and Islam, fell foul of the new authorities.
A number of PMOI leaders were executed and in 1981 the leadership was forced to decamp to Paris. The early 1980s saw assassinations of top Iranian officials, generally attributed to the group.
The PMOI set up Camp Ashraf in the late 1980s, when it was welcomed by Iraq's then-president, Saddam Hussein, who was fighting a war against Iran. Its military wing fought alongside Iraqi soldiers.
After the US-led invasion of Iraq in 2003, PMOI members agreed to disarm. But Iraq's new Shia-led government insisted the group leave.
In September 2012, the US government removed the PMOI from the state department's list of designated terrorist organisations, in part because of its co-operation in the move to Camp Hurriya.