The US government on Monday said it had approved the sale to Iraq of $600 million in tank ammunition manufactured by General Dynamics Corp, saying it would help the Iraqi government establish an integrated ground defence capability.

Congress now has 30 days to block the sale, although such action is rare since arms deals are usually vetted carefully before a congressional notification.

The Pentagon's Defense Security Cooperation Agency, or DSCA, notified lawmakers that the State Department had approved the sale of 10,000 M831 120m, high-explosive anti-tank munitions, 10,000 M865 120mm kinetic energy warheads and 26,000 other munitions, as well as logistics services.

DSCA said the prime contractor would be General Dynamics, maker of the M1A1 Abrams tank and the requested munitions.

The U.S. military has been conducting air strikes against Islamic State militants in Iraq and Syria, and is seeking to strengthen the Iraqi government so it can resist the extremists more effectively.

On Monday, Islamic State militants disguised as Kurdish peshmerga fighters advanced on the Iraqi town of Qara Tappa, while a suicide bomber killed 11 and wounded 28 others inside a Shi'ite Muslim mosque in central Baghdad. – Reuters