Unknown gunmen shot dead a brigadier general in the intelligence service and an interior ministry lieutenant colonel in Baghdad on Saturday morning, Iraqi security officials said.

"Unknown gunmen with silenced weapons killed a brigadier general in the intelligence service, Abdul Razzaq Khalaf," an interior ministry official said on condition of anonymity.

The attack took place when Khalaf was driving in the Jamiyah area of west Baghdad, the official said, adding that Khalaf was shot twice in the head.

In a separate attack, gunmen, who also used silenced weapons, killed interior ministry Lieutenant Colonel Saad Mohsen Alwan in Shuala in north Baghdad, the official said.

The attacks took place on Saturday morning, said a military source who also spoke on condition of anonymity.

Despite a decline in violence nationwide since its peak in 2006 and 2007, attacks remain common. A total of 185 Iraqis were killed in violence in September, according to official figures.