(AFP) -- Mosul, Iraq's second city, was retaken from Isis in July after a massive months-long offensive.

"Waad Allah forces are repelling an Isis attack southwest of Mosul in the Hatra desert" some 100 kilometres (60 miles) southwest of Mosul, said a spokesman for the Hashed unit.

The Hashed is an umbrella group of paramilitary auxiliaries formed in 2014 to support Iraqi regular forces after Isis swept across swathes of northern Iraq.

In a series of online posts, Waad Allah said Isis sent "numerous suicide bombers" to attack its forces, and gave a death toll of 24 terrorists and four of its own men.

Iraqi forces have retaken more than 90 percent of the territory Isis seized in the country in 2014, with the terrorists now confined to the desert areas in Anbar province bordering Syria.

But despite a series of stinging defeats, Isis in Iraq retains the ability to launch attacks in areas declared "liberated" months previously.

After losing Mosul in July, Isis has also just lost Raqqa, its "capital" in Syria.

The Hashed took over the Hatra area in April this year after Isis forces were ousted.

The ancient walled city of Hatra in northern Nineveh province is on the UNESCO World Heritage List.

(Photo: Fighters of the Hashed al-Shaabi coalition of Iraqi paramilitary forces have been instrumental in fighting around Mosul, AFP)