The United States condemned an attack in which 47 people were reportedly killed at a large refugee camp in eastern Iraq on Sunday, and the United Nations demanded an investigation into the incident.
"The United Nations deplores the tragic events at Camp Ashraf today. A number of residents have been reportedly killed and injured," a statement from the international organization read.
The UN urged the Iraqi government to "immediately investigate the facts and disclose their findings."
Camp Ashraf is home to some 3,400 refugees, primarily members, relatives and sympathizers of Iran's main opposition group, the People's Mujahedin Organization of Iran, also known as MEK.
The violence took place hours after a mortar bomb attack on the camp -- which the dissident group Mujahadin-e-Khalq (MEK) blamed on the Iraqi army, according to Reuters.
Two Iraqi security sources told Reuters that security forces opened fire on residents who had stormed a post at the entrance to Camp Ashraf, a site that Iraq's government wants closed down.
An adviser to Iraqi Prime Minister Nuri al-Maliki said the reports were untrue, according to Reuters.
"We want to know the truth," adviser Ali al-Moussawi said, adding that it was unclear what had caused a blast reported at the camp.
Moussawi told Reuters that camp residents could have been killed in the explosion or through infighting, adding that Maliki had ordered an investigation.
U.N. Secretary General Ban Ki-moon appealed for the urgent restoration of security in the camp -- and expressed his condolences.
"The Secretary-General deplores the tragic events in Camp Ashraf today that have reportedly left 47 killed," the statement read. "He expresses his sorrow and extends his deepest condolences to the families of the victims."
MEK said some residents were machine-gunned with their hands tied behind their backs, according to Reuters.
The U.S. State Department condemned the attack and called on the Iraqi government to ensure residents' safety.
"We underscore the responsibility of the Government of Iraq and all relevant stakeholders to ensure the safety and security of residents at both Camp Ashraf and Camp Hurriyah, and we affirm the call by UNAMI [United Nations Assistance Mission for Iraq] for a full and independent investigation into this terrible and tragic event," the State Department's deputy spokeswoman Marie Harf said.
"Those found to be responsible must be held fully accountable," she said, adding, "We further call on Iraqi authorities to act with urgency to immediately ensure medical assistance to the wounded and to secure the camp against any further violence or harm to the residents."
Reuters contributed to this report.