Two people were killed in a mortar attack on an Iranian dissident camp in the Iraqi capital on Saturday, police sources said.
The Mujahadin-e-Khalq (MEK) group, said a further 27 people were wounded in the attack. A similar attack in February killed at least five of its members.
It was not immediately clear who carried out the attack.
MEK, which was removed from the U.S. State Department's official list of terrorist organisations last year, calls for the overthrow of Iran's clerical leaders and fought on Iraq's side in the Iran-Iraq war during the 1980s.
It is seeking to recast itself as an Iranian opposition force but is no longer welcome in Iraq under the Shi'ite Muslim-led government that came to power after U.S.-led forces invaded and toppled Saddam Hussein in 2003.
The United Nations intends to process them for refugee status in other countries.
Police said 11 Iranian nationals inside the camp and six Iraqis outside it had been wounded.
"At around 11:30 a.m. around 5 mortar rounds landed in and near the Iranian camp in western Baghdad, killing two Iranian persons and wounding more than 17," said a police source at Baghdad airport, which is near the camp.