Iraqi police say six people were killed when attackers fired rockets at a refugee camp for an Iranian exile group outside Baghdad.
More than 40 people were injured.
There was no immediate claim of responsibility for the February 9 attack on the camp, a former U.S. military base known as Camp Liberty.
The camp hosts some 3,000 people linked to the Mujahedin-e Khalq Organization (MEK), the militant wing of the Paris-based National Council of Resistance of Iran.
The camp is meant to be a temporary way station while the United Nations works to resettle the residents abroad.
They are unlikely to return to Iran because of their longtime opposition to the theocratic regime.
The United Nations special envoy to Iraq Martin Kobler called for an immediate investigation.
Based on reporting by AP and AFP