Photo: AFP    

Kurdish forces backed by coalition air strikes have repulsed the most serious attack by Islamic State group in Iraq in five months, US officials say, the BBC reports.

IS militants mounted a co-ordinated assault on several locations near the northern city of Mosul on Wednesday.

About 180 IS fighters were killed in the strikes that continued until Thursday morning, the US officials said.

Mosul has been under the control of IS since last year.

Militants began attacking Iraqi Kurdish Peshmerga positions late on Wednesday afternoon, using machine guns, car bombs, rockets and armoured bulldozers, Kurdish and US officials said.