Iraq declared on Thursday that its forces had retaken the northern city of Tal Afar and the surrounding region, in another major victory over Islamic State group jihadists.

IS, which seized nearly a third of Iraq in 2014 in a humiliating defeat for the army and police, now controls barely 10 percent of the country, according to the US-led international coalition ranged against the jihadists.

The fall of Tal Afar, located in the northern province of Nineveh, deprives IS of what was once a key supply hub between its territory in Iraq and neighbouring Syria.

After a 12-day battle by Iraqi forces backed by coalition air strikes and Shiite paramilitary fighters, Prime Minister Haider al-Abadi announced that Tal Afar had "regained its place in the national territory".

He vowed to liberate "every inch of Iraqi territory" from the group.

"We say to the criminals of IS: wherever you are, we're coming to liberate it and you have no choice but to die or surrender," Abadi said.

The full recapture of Nineveh province comes weeks after Iraqi forces ousted the jihadists from the provincial capital Mosul, three years after the jihadists declared a self-styled "caliphate" straddling Iraq and war-torn Syria.

As promised by Iraqi officials, the victory also comes in time for the Muslim feast of Eid al-Adha, which starts on Friday for Iraqi Sunnis and on Saturday for Shiites.

Andrew A. Croft, deputy commander of the coalition, said the speed with which Tal Afar and surrounding areas were retaken was a "positive sign".

It showed "the Iraqi forces' abilities against IS in Iraq. They have proven that the (coalition's) strategy is working," he said.

- 'Stunning victory' -

IS has lost much of the territory it controlled in the two countries and thousands of its fighters have been killed since late 2014, when the coalition was set up to defeat the group.

But the jihadist group, which is also known as ISIS, continues to claim attacks in the Middle East and Europe.

In a statement, the coalition against IS congratulated Abadi and the Iraqi security forces "on their stunning victory in Tal Afar" and Nineveh province.

But it cautioned that "dangerous work remains to completely remove explosive devices, identify ISIS fighters in hiding and eliminate any remaining ISIS holdouts so they do not threaten the security of Tal Afar in the future."

Croft said Iraqi forces had killed between 600 and 700 IS fighters during the battle for Tal Afar while around 100 more had surrendered.

IS fighters in Iraq now control only the town of Hawija around 300 kilometres (185 miles) north of Baghdad, as well as several areas in the vast western desert province of Anbar along the border with Syria.

- Shiite enclave -

IS jihadists overran Tal Afar, a Shiite enclave in the predominantly Sunni province, in June 2014.

The city lies around 450 kilometres (240 miles) northwest of the capital Baghdad and about 70 kilometres (40 miles) west of Mosul, Iraq's second city.

At the time Tal Afar had a population of around 200,000, but it was unclear how many remained when the battle to recapture the city was launched on August 20.

Officials have said the swift capture of Tal Afar would make it even more difficult for the jihadists to transport fighters and weapons between Iraq and Syria.

Authorities had accused the approximately 1,000 jihadists believed to be in the city when the operation was launched of using civilians as human shields during Iraqi and coalition air strikes.

Progress in Tal Afar was far more rapid than in Mosul, Iraq's second city which fell only after a gruelling nine-month battle that began in October 2016.

IS has also suffered major losses in Syria, where US-backed fighters have retaken more than half of the group's de facto Syrian capital Raqa.

Iraqi authorities are now expected to launch a new offensive against IS in their stronghold of Hawija in Kirkuk province.

But the battle for the town is expected to be more complicated because of its location.

Oil-rich Kirkuk province is at the centre of a long dispute and a source of lingering tensions between the Iraqi federal government and regional Kurdish authorities.

An offensive targeting Hawija could also be postponed due to a referendum on Kurdish independence planned for September 25 -- which Baghdad has called "untimely".