A teenager who had been recruited by the Islamic State in Mosul killed the whole of his six-member family when his explosive belt went off inside their home east of the city.

Three children were reportedly among those killed by the unnamed boy's explosive device.

The boy, who belonged to the so-called 'Cubs of the Caliphate' squad, had been given the suicide belt by other members of the terror group, Alsumaria News reports.

He put the device on and went back to his home in the al-Wehda district of Mosul, where it later exploded, a source told the news channel.

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Members of the Iraqi forces drive a BMP-1 infantry fighting vehicle as they hold a position in the village of Jarif, some 45 kilometres south of Mosul

'The teenager's belt exploded inside his home. It appeared later that all of his family, including three children, were killed,' said the source, on condition of anonymity.

The man said Islamic State regularly recruits teenagers to wear explosive devices, especially in eastern Mosul.

'It comes as part of ISIS strategy to strengthen its grip on the ground and intimidate the people,' he added.

The extremist group has a history of recruiting underage fighters, some of whom have appeared in the group's propaganda videos, with children even taking on the role of executioner.

ISIS has been fighting to retain control of Mosul, which the terror group took over in June 2014.

Iraqi forces keep their position at the Nimrud town during the operation to retake Mosul from Islamic State

It had been declared the capital of the self-proclaimed 'Islamic Caliphate' but the extremist group is being pushed out of the city after Iraqi troops and US-led air forces launched an operation to liberate the city last month.

Today, Iraqi special forces said Islamic State militants battling to regain control of Mosul have fired mortar rounds on government-controlled neighborhoods in the east of the city, killing at least seven civilians.

Iraqi special forces soldiers fire weapons at Islamic State fighters in the battle for Mosul

Army medic Bashir Jabar, in charge of a field clinic run by the special forces, said IS attacked the city's eastern Tahrir neighborhood and nearby areas as civilians were fleeing to camps sheltering displaced families.

Mr Jabar said two children were among those killed, while 35 people were wounded, including 18 children.

On a donkey-drawn wood cart, a grieving family carried the body of their 18-year-old son, wrapped in a white plastic bag.