Iraqi Kurdish regional president Massud Barzani has announced the "liberation" of the town of Sinjar in a major operation against the so-called Islamic State 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.

The lightning assault, which also involved fighters from the Yazidi minority that IS has brutally targeted in the Sinjar area, began yesterday morning.

Kurdish forces were able to cut Highway 47, one of the IS's main supply routes to neighbouring Syria, which runs past Sinjar, and entered the town the following day.

However, Mr Barzani's remarks also made clear the battle for Sinjar was likely to be followed by political conflict.

"Sinjar was liberated by the blood of the peshmerga and became part of Kurdistan," Mr Barzani said.

The Iraqi government, which has long opposed Kurdish leaders' ambitions to expand their autonomous region by incorporating a swathe of neighbouring historically Kurdish-majority territory, is unlikely to welcome the idea of Sinjar becoming part.

Non-peshmerga groups that have fought IS in the Sinjar area, including Yazidi groups and Syrian Kurdish fighters from the People's Protection Units, may resent Mr Barzani's assertion of peshmerga primacy and control over the area.

Meanwhile, at least 19 people have been killed in a series of bomb attacks targeting Shia Muslims in Baghdad.

A suicide bomber has killed at least 17 people at a Shia funeral in a mosque in the Iraqi capital, Baghdad, according to security and medical officials.

The attack in the Al-Ashara al-Mubashareen mosque in the Amil area of south Baghdad also wounded at least 33 people, the officials said.

Two officials said the funeral was for a member of the volunteer paramilitary force known as the Popular Mobilisation units.

There was no immediate claim of responsibility for the attack, but suicide bombings are a tactic used exclusively by Sunni extremists in Iraq, including the so-called Islamic State group, who consider Shias to be heretics.

The Popular Mobilisation units - which are dominated by Iranian-backed Shiite militias - are some of the most effective forces in the battle against IS, which overran large parts of the country last year.

A further two people were killed when two roadside bombs exploded in Sadr City area of north Baghdad near a Shia place of worship.

Nine people were wounded in the attack.