Several hundred Turkish soldiers have been deployed to provide training for Iraqi troops in an area near the northern Iraqi city of Mosul, which is under Islamic State control, a Turkish security source said Friday.

Islamic State militants overran Mosul, a city of more than 1 million people, in June 2014, but a much anticipated counteroffensive by Iraqi forces has been repeatedly postponed because they are involved in fighting elsewhere.

"Turkish soldiers have reached the Mosul Bashiqa region. They are there as part of routine training exercises. One battalion has crossed into the region," the source said, declining to say exactly how many soldiers had been deployed.