BAGHDAD (AP) — A barrage of rockets slammed late Thursday into a former military base near the Baghdad International Airport that houses an Iranian refugee group, killing three Iraqi soldiers, officials said. The Iranian exiles said at least 20 of their people died in the attack.

Iraqi police said 16 rockets hit Camp Liberty, a former U.S. base that now houses the exiled Iranian opposition group known as the Mujahedeen-e-Khalq. They said at least 16 soldiers guarding the camp were also wounded while the Iranian group, known as MEK, said dozens of Iranian refugees were wounded as well.

No one immediately claimed responsibility for the attack.

The statement from Mujahedeen-e-Khalq said that "due to darkness of the night, the exact number of dead and wounded has not been established."

Police said that there may be casualties among the exiled group, but noted they did not report them to the local authorities so they could not determine how many civilians were hit in the attack. The MEK statement on casualty figures could not be independently verified because of the late hour of the attack and the camp's inaccessibility to media.

A police official added that the rockets landed far enough from the airport that they did not disrupt commercial traffic. A hospital official confirmed the casualty figures. Both officials spoke on condition of anonymity because they were not authorized to speak to the media.

This was not the first attack since Camp Liberty became home to the Iranian group, which is strongly opposed to Iran's clerical regime. Last year, the Islamic State group was said to have fired rockets near to Baghdad International Airport as it attempted to destabilize the capital.

Members of the Mujahedeen-e-Khalq were welcomed into Iraq by Saddam Hussein in the 1980s during the brutal war with neighboring Iran. Their fortunes turned sharply with the Iraqi dictator's toppling in the 2003 U.S.-led invasion.

Iraq's current Shiite-led Iraqi government, which has strengthened ties with Tehran, considers their presence in the country illegal.

The group regularly reports worsening health conditions within their isolated camp and accuses the Iraqi government of neglect and human rights abuses.

Associated Press writer Murtada Faraj contributed to this report from Baghdad.