A plume of smoke rises above a building during an air strike in Tikrit March 27, 2015. REUTERS/Thaier Al-Sudani

DUBAI (Reuters) - U.S. and coalition forces are likely to increase air strikes against Islamic State targets in Iraq and Syria in coming weeks after a lull in September and October, the head of U.S. Air Forces Central Command said Saturday.

Lieutenant General Charles Brown told reporters at the Dubai International Air Chiefs Conference that the reduction in air strikes was due to weather and to a slowdown in activity on the ground and not due to the start of Russian air strikes in the region.

He said both government forces and insurgents were increasing their ground movements, which could create more opportunities for the United States and its allies to carry out more air strikes against Islamic State targets.

"If they're not out and about, it's harder to strike, particularly for an adversary that may wrap themselves in the civilian population," he said.

Brown also rejected criticism that the United States was not using air strikes as much or effectively as possible, saying coalition forces were striving to avoid civilian casualties that could help recruitment for Islamic State.

He also noted that the sheer number of air strikes was less of an indicator than the targets hit and the number of weapons used.

The United States and its allies targeted Islamic State in Iraq with 14 air strikes on Thursday, and also hit the militant group with nine air strikes in Syria, the U.S. military said on Friday.

Brown told reporters that an agreement signed with Russia to avoid possible mid-air collisions was working well, and no incidents had been reported.

"They don't want a mid-air and neither do we," he said.

He said the agreement did not hinder U.S. forces from carrying out strikes where needed.

"We've said we're going to fly where we need to get the job done," he said.

(Reporting by Andrea Shalal; editing by Jason Neely)