Rockets and mortar rounds have struck a refugee camp for Iranian exiles next to Baghdad's international airport, killing six people and wounding about 40, police and UN officials say.
The UN urged the Iraqi government to ensure the safety of the about 3100 camp residents and move quickly to find the still-unidentified attackers.
The government said it launched an investigation, but that there is little it can do to shield the camp from rocket attacks. It asked the international community to speed up the resettlement of the refugees.
The camp is home to members of Mujahedeen-e-Khalq or MEK, the militant wing of a Paris-based Iranian opposition group, the National Council of Resistance of Iran.
Iraq's Shiite-led pro-Iranian government considers the MEK a terrorist group and is eager to have it out of the country.
The refugee camp, located in a former American military base known as Camp Liberty, is meant to be a temporary way station while the United Nations works to find host countries for the refugees. They are unlikely to return to Iran because of their opposition to the regime.
In Saturday's attack, 35 rockets and mortar rounds struck the camp, said camp spokesman Shahriar Kia.
He said more than 100 people were hurt, while the UN and police put the number of injured at about 40.
The Iranian opposition group provided amateur video and photos it said showed the aftermath of the attack. One photo showed five bodies swaddled in blankets lying on the ground in a hallway.
A video clip showed wounded, some with blood-covered faces, being treated at a small clinic. Other footage said to be from the camp showed several small craters in the ground, presumably from rockets, as well as shattered windows and shredded walls of trailer homes.
The UN High Commissioner for Refugees, Antnio Guterres, called on the Iraqi government to ensure the safety of the refugees and find the perpetrators. "This is a despicable act of violence," he said, noting that camp residents are asylum seekers requesting refugee status and are entitled to international protection.
Two police officials confirmed that six people were killed in Saturday's attack and said more than 40 were hurt, including three Iraqi policemen. They spoke anonymously because they were not authorised to share information with the media.
Kia, the camp spokesman, alleged that Iraqi authorities refused to let the wounded be taken to area hospitals for treatment.
Iraqi government spokesman Ali al-Moussawi denied the claim.
The UN envoy to Iraq, Martin Kobler, said about 40 wounded were taken to hospitals shortly after the attack.
Kobler said five people died at the camp and that a sixth apparently died later in a hospital.
The camp was set up last year.
Before being moved to the Baghdad area, members of the MEK had lived in another camp, called Ashraf, in northeastern Iraq. Camp Ashraf was twice raided by Iraqi security forces trying to impose control, leaving more than three dozen people dead.
Iraq's government says MEK members are living in Iraq illegally.
"We call on the international community to expedite the procedures ... to find countries for them as quickly as possible," al-Moussawi, the government spokesman, said Saturday.
Kobler told The Associated Press that about half the camp residents have so far been cleared for resettlement, and that he believes the first group can leave soon.
The MEK, which is also called the People's Mujahedeen of Iran, opposes Iran's clerical regime and has carried out assassinations and bombings in Iran. It fought in the 1980s alongside Saddam Hussein's forces in the Iran-Iraq war, and several thousand of its members were given sanctuary in Iraq by Saddam.
The group renounced violence in 2001 and the Obama administration took the MEK off the U.S. terrorism list in late September.