WASHINGTON (REUTERS) - A Kurdish referendum for independence has decreased focus on fighting Islamic State militants in Iraq, a spokesman for the US-led coalition fighting the militant group said.

"The focus which used to be like a laser beam on ISIS is now not 100 per cent there, so there has been an effect on the overall mission to defeat ISIS in Iraq as a result of the referendum," said coalition spokesman Colonel Ryan Dillon, using an acronym for Islamic State.

Dillon added that there had been no impact on current military operations out of Erbil's airport.