Iraqi forces begin operation to retake IS-held Tal Afar

Iraqi forces lanched an operation to retake Tal Afar, west of Mosul, from the Islamic State group, one of the militants' last strongholds in Iraq.

Prime Minister Haider al-Abadi said IS fighters holed up in the town now have "no option" but to surrender or die.

Dressed in military uniform and standing in front of an Iraqi flag and map of Iraq, Abadi announced "the start of an operation to free Tal Afar".

"I am saying to [IS] that there's no choice other than to leave or be killed," he said. 

"We have won all our battles, and Daesh have always lost."

Tal Afar and the surrounding area is among the last pockets of IS-held territory in Iraq after victory was declared against the group in July in Mosul, the country's second-largest city.

The town, about 150 kilometres (93 miles) east of the Syrian border, sits along a major road that was once a key IS supply route.

Aid groups have warned the operation could trigger a humanitarian crisis as airstrikes are stepped up and thousands of troops and militants gather outside Tal Afar.

Federal police and special forces are on the outskirts of the town, as are government-allied militants from the Hashd al-Shaabi (Popular Mobilisation Forces).

IS jihadists overran Tal Afar - a Shia enclave in the predominantly Sunni province of Nineveh - in June 2014.

At the time there were around 200,000 in the town, but the number left in Tal Afar is not known.

Authorities believe there are around a thousand IS fighters holed up in the town and using the civilian population as human shields.