Iraqi Kurdish regional president Massud Barzani on Friday announced the "liberation" of the town of Sinjar in a major operation against the Islamic State jihadist group.

"I am here to announce the liberation of Sinjar," Barzani told a news conference near the northern town.

Speaking in Tunisia around the same time, US Secretary of State John Kerry said he was "absolutely confident" the town would be freed in the operation by Kurdish peshmerga backed by US-led air strikes and ground spotters.