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.

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.

"This was the hardest punch Isil [IS] had thrown since this summer, and the Peshmerga defeated them," said Col Steve Warren, a US military spokesman, according to the Washington Post.

Brig Gen Mark Odom, the senior US officer in Iraq, said the assault may have been a "spoiling attack", the New York Times reported, suggesting it may have been an attempt to disrupt plans to retake Mosul.

Among the sites targeted by IS was Bashiqa, where Turkish forces have recently been training Iraqi Kurds, sparking a row with the Iraqi government.

Meanwhile at the UN the 15-member Security Council adopted a resolution aimed at starving IS of funds.

It urges countries to "move vigorously and decisively to cut the flow of funds" to IS, such as by preventing its smuggling of oil and antiquities.

(BBC)