France will host an international meeting Thursday on the future of Mosul, French Foreign Minister Jean-Marc Ayrault said on the second day of a major offensive to retake Iraq's second city from the Islamic State group.

"We must anticipate, plan for the 'day after', and the stabilisation of Mosul after the military battle," Ayrault said Tuesday, adding that Iran -- which wields substantial influence in Iraq -- was not invited to the talks.

"We must win the war but also look at everything that will enable us to win the peace," he said.

The French foreign minister said the international coalition fighting IS also had a "responsibility" to retake Raqa, in Syria, which would be the last major city in either country under the group's control if Mosul falls.

"Not to go on to Raqa would be a bad mistake," Ayrault told reporters.

"If we want to fight effectively against terrorism it is essential to take this city."

The long-awaited offensive on Mosul was launched on Monday, with some 30,000 forces involved in Iraq's largest military operation since the pullout of US troops in 2011.

The US military, which is leading a coalition providing air and ground support, said Iraqi forces looked "ahead of schedule" but warned the battle would be long and difficult.

Read more at AFP.