Baghdad (CNN) -- Iraq defends its actions at a refugee camp sheltering Iranian dissidents, saying Friday it imposed "law and order" after members of an exile group there attacked Iraqi security forces.
The incident occurred at Camp Ashraf in Diyala province, where the People's Mujahedeen of Iran is based. The PMO, also known as the Mojahedin-e Khalq Organization, has opposed the Iranian government for decades.
The Iranian exiles in Iraq said that Iraqi security forces invaded their refugee camp and killed at least 31 people. Hundreds more were injured in the assault at Camp Ashraf, the PMO said.
But Iraqi government spokesman Ali al-Dabbagh said members of the PMO left the camp and hurled stones at security forces, wounding five of them. He said the rioting required forces to bring residents back to the camp.
"While the Iraqi government warns members of this organization from violating the law and public order, the government will deal with them ... according to the laws of Iraqi country," al-Dabbagh said.
Iraqi army officials in Diyala province said they did not use live ammunition. The officials said Ashraf residents armed with shovels and throwing stones approached longstanding Iraqi positions around the camp and provoked the conflict.
Mark Toner, the acting deputy State Department spokesman, said the United States "is deeply troubled" by the reports of violence and casualties.
"Although we do not know what exactly transpired early this morning at Ashraf, this crisis and the loss of life was initiated by the government of Iraq and the Iraqi military," he said in a statement. He did not elaborate.
Ashraf residents and their supporters are calling the event a "massacre."
People's Mujahedeen representatives have posted videos online showing what appear to be Iraqi troops shooting at small crowds of men and at least one case of a military vehicle ramming into a man. They also show at least seven dead and an unclear number of wounded men.
CNN could not confirm that the videos, which are edited, were filmed at the camp overnight.
The U.S. Embassy in Baghdad said officials there are "monitoring the situation at Camp Ashraf and are in contact with the government of Iraq," and urged "all sides to exercise restraint."
In July 2009, similar clashes between citizens of Camp Ashraf and Iraqi police led to the deaths of 12 residents. The camp has been the subject of debate in Iraq since American forces relinquished control of it in 2009.
The Iraqi government has previously proposed dismantling the camp, a move its residents strongly oppose, as they fear being deported to a hostile Iran.
Since the U.S.-led invasion in 2003, relations between Iran and Iraq have improved. A majority of Iraq's new government is composed of Shiite Muslims, the majority religion in Iraq.
Some top Iraqi government officials lived in Iran in the Saddam Hussein era.
Iran has long urged Iraq to get rid of Camp Ashraf and the opposition group there, and Iraq's failure to do so is a point of tension between the two countries.
Tehran considers the PMO to be a terrorist outfit, as does the United States. The European Union does not.
CNN's Mohammed Tawfeeq reported from Baghdad, and Alden Mahler Levine from Atlanta.