At least four people have been killed and 12 wounded after a car bomb exploded outside the offices of a Sunni Arab political party in the western Iraqi city of Fallujah, a police officer said.
The bombing on Saturday, which apparently targeted the offices of the Iraqi Islamic Party, also damaged nearby shops and a private health clinics,
A police officer, who spoke on condition of anonymity, said that all the casualties appeared to be civilians.
Security forces cordoned off the city, preventing individuals and vehicles from entering or exiting, in the aftermath of the attack.
The security situation in across Anbar province - once a stronghold of Sunni-led attacks on foreign troops and government targets - has improved dramatically since tribal fighters decided in 2006 to turn against al-Qaeda and other groups.
The attack comes less than a month after US troops withdrew from urban centres in line with a security pact between Baghdad and Washington that calls for US forces to leave Iraq by the end of 2011.
Violence had dropped markedly throughout Iraq, but attacks increased in the run-up to the pullback, with 437 Iraqis killed in June - the highest death toll in 11 months.
On Tuesday, Iraqi officials declared a rare vehicle ban across Anbar after two bomb attacks killed three people in the Ramadi, the provincial capital. The previous day, an explosion had killed two police officers in the city.
Elsewhere on Saturday, a bomb planted on a car in the Adhamiya neighbourhood in northern Baghdad, the capital, killed one person and wounded another, police said.