Mass graves containing at least 400 suspected Islamic State group victims have been found in the disputed Iraqi province of Kirkuk, Iraqi authorities said.

The string of grisly discoveries was made on Saturday at a military base around two miles (three kilometres) from Hawija in northern Iraq. The base was used by US troops prior to 2011.

Jihadists had turned the city ‘into an execution ground’ after seizing the territory in 2014, Kirkuk governor Rakan Saeed said.

‘Not less than 400 people were executed,’ he said, adding that some were clad in the uniform of prisoners condemned to death while others wore civilian clothing.

‘We are standing here, where … at least 400 civilians were dragged, some in their red jumpsuits, and brutally executed by ISIS,’ he added.

Colonel Murtada Abbas of the 60th Brigade in the Iraqi military said that people who had witnessed the executions led authorities to the graves.

The governor of Kirkuk has asked the Iraqi government and the Commission of Human Rights to work to try to identify the victims.

IS was forced out of Hawija – 150 miles (240 kilometres) north of Baghdad – by Iraqi forces in October in a sweeping offensive that has seen the group lose the vast bulk of territory.

Iraqi troops and Kurdish forces drove IS from the northern town of Hawija on October 10 after nearly three weeks of fighting. Hundreds of IS fighters and their families surrendered.

It was the last major unified operation by Iraqi federal forces and Kurdish forces known as the peshmerga. Full Report