"We know that there have been small numbers killed in these engagements, some have been wounded as well," he said at the US Central Command's war headquarters at As-Saliyah, Qatar.

"There were some shootings that occurred," Brooks said.

"There were some more that occurred yesterday in violent actions at a bank, that involved police and also some coalition forces. A two-way exchange of fire ensued, police were wounded by fire and Marines were involved in returning fire," he said, adding that "some suspected bank robbers were killed and others were wounded."

Witnesses say 15 people were killed and 28 wounded on Tuesday and Wednesday, but Brooks did not give a figure, after saying earlier that up to seven people were shot dead by US troops on Tuesday when they fired on an unruly crowd.

"Our approach is deliberate, it's an effort to maintain law and order ... it's in response to threats that are directed to coalition forces," the general said.

"Our coalition forces have an inherent right to self-defense," he added.

"There are pockets still of lawlessness, violence and indications of deliberate agitation to create those conditions."

SPACE.WIRE