Kurdish fighters in Iraq have pushed deeper into the town of Sinjar, held by the Islamic State group, but are facing stiff resistance from the Sunni militants who captured it in August.

One of the fighters, Bakhil Elias, says clashes overnight and on Monday have been "fierce" and that IS militants are using snipers. At least two Kurdish peshmerga fighters have been killed by snipers and 25 were wounded in the latest fighting.

Large plumes of black smoke are billowing into the sky from inside the town.

The Kurdish forces say the militants are burning tyres and oil to create a smoke screen with the thick dark clouds and obstruct airstrikes against their positions by the U.S-led coalition.

Last week, the Kurdish peshmerga fighters launched the operation to retake Sinjar.