US-led coalition preparing 25,000-strong Iraqi-Kurdish force to retake Mosul from IS in April

A joint Iraqi-Kurdish force comprising about 25,000 soldiers is being set up to retake the northern Iraqi city of Mosul from the Islamic State (IS), a U.S. official said.

A senior military official said that the operation is would probably take place in April or May.

According to the BBC, telegraphing the timing of the attack was unusual, but the U.S. insisted that since the IS was retreating, Washington needed to show its efforts to rebuild Iraqi military capacity was bearing fruit.

The official conceded that no decision has been made on whether a small group of U.S. military advisers would be required on ground to direct air support but added that the all the fighters in the military force would have undergone training by the U.S.

The revelation comes after Iraq's Prime Minister Haider al-Abadi declared that his forces were preparing to launch an offensive in Mosul. He had said that he hoped that the city would be retaken in a few months' time and with a minimum of casualties.

Mosul is Iraq's second largest city which fell into the hands of the IS last June.