Baghdad's counter-terrorism service (CTS) said it had retaken full control of Bartalla on Thursday as part of a major battle announced this week to retake the jihadist group's last major Iraqi stronghold of Mosul.

However, elite forces returning from missions inside the town on Friday said they had encountered pockets of resistance and IS fighters were using tunnels to fight back.

"We'll allow civilians to enter and see their houses after securing the town entirely," CTS General Maan al-Saadi said, as columns of black smoke billowed from the town.

The general did not allow the press into Bartalla on Friday, as he said troops were combing it for bombs left behind by jihadists in cars, houses or by the sides of roads.

A wide array of Iraqi and international forces are involved in the campaign to retake Mosul -- some 15 kilometres (9 miles) to the east of Bartalla -- that was announced by Prime Minister Haider al-Abadi early Monday.

These include peshmerga forces from Iraq's autonomous Kurdish region.

While Iraqi soldiers and counter-terrorism forces have been fighting inside Bartalla, peshmerga fighters -- some originally from the town -- have remained behind the front line at the town's edge.

A military camouflage bandana wrapped around his forehead and cartridge belt slung over his shoulder, peshmerga fighter Jassem Mohammed Naqib strained to see the fighting for his hometown in the distance.

- 'I will see my home' -

The 25-year-old, who has fought for the peshmerga for nine years, this week managed to transfer to the Bartalla front in the hope of seeing his home again after fleeing it with his wife and three children in mid-2014.

"Today, I will finally be able to see my home, God willing," he said, after fleeing in the middle of a hot summer's night two years ago after jihadists entered Bartalla.

"I have no idea what state I'm going to find it in," he added of his house in the town that was predominantly Christian before IS swept in.

The sound of explosions and bursts of gunfire resounded on the town's outskirts on Friday.

Dressed in a black shirt and grey jacket, the town's mayor -- who also fled Bartalla with his wife and 14 children in 2014, leaving everything behind -- tried to assess the damage from afar.

"From what we have managed to gather, they have destroyed public buildings and infrastructure," Ali Mohammed Fathi said, and urged the international community to help rebuild.

Hassan Adnan Hassan, another Kurdish fighter, said he wanted to enter the town to check on his cousin's house.

"He asked me to come and see it, to check if it had been blown up," the 20-year-old said, wearing a khaki helmet and a Kurdistan flag on his right sleeve.

Hassan had fled his own home in the nearby town of Qaraqosh, which was once Iraq's largest Christian town.

According to local official Nissan Karroumi, around 60,000 people of all confessions lived in both Qaraqosh and Bartalla before the jihadists overran the area and prompted residents to flee.

"I will take part in all battles, defending Kurdistan until my last breath," said Karroumi, who has been fighting with the peshmerga for five years.

Naqib said he was fighting for his children, whom he had seen on Thursday after receiving long awaited leave from fighting, he said.

"We came to fight for our land, our belongings and our honour," he added.