French fighter jets have set off on a mission against Islamic State in its Iraqi stronghold of Mosul.

Eight jets took off from the aircraft carrier Charles de Gaulle in the eastern Mediterranean in preparation of an offensive backed by Britain and the US to liberate the city.

Iraqi forces will lead the operation, backed by western special forces and aircraft including the RAF, once it starts - possibly in October.

A French defence official said Friday's mission "in no way" marked the beginning of the battle to retake Mosul.

Mission to liberate Iraqi city of Mosul imminent

However, it is unclear whether the jets will carry out airstrikes or reconnaissance.


French radio station RTL reported the warplanes were armed with four 250kg laser-guided bombs each, and that the operation would involve an attack on average every three minutes.

US and British drones have been flying constant surveillance missions over the city.

They have witnessed senior IS leaders flee, but intelligence reports estimate there are between 2,500 and 3,000 fighters left.

Image: Mosul is important to IS and symbolic of the terror group's early gains

The Pentagon is hoping to obtain a raft of intelligence on IS, including its foreign networks, during the offensive.

Many of the 615 additional soldiers Washington is sending to Iraq are intelligence specialists who will help the Iraqis use any intelligence gathered from the northern city as quickly as possible.

"When you free a city like Mosul, you can expect a tremendous lot of intelligence," Colonel John Dorrian, a coalition spokesman, said from Baghdad.

The French mission comes after Iraqi forces retook two villages on the border of Nineveh and Salahuddin provinces from IS earlier this month as part of a broader operation to secure supply lines ahead of a move on Mosul.

ISIS Militants Parade Through Mosul

The International Committee of the Red Cross has warned up to one million Iraqis could be forced to flee their homes as the war intensifies against IS.

The flight of so many people could pose a "massive humanitarian problem" for Iraq, the Geneva-based aid group said.

More than three million civilians are already displaced inside the country and 10 million people are in need of assistance.

Around Mosul, the United Nations is preparing for what it has described as the largest relief operation so far this year to provide food, water and shelter for people fleeing the area.

The British government has begun moving aid into northern Iraq in anticipation.

US-backed government forces have trained their sights on Mosul since retaking full control of Fallujah, 30 miles west of Baghdad, after a vast operation against IS in May.