An offensive to encircle Iraq's second city of Mosul should begin "in the next few weeks", Britain's Defence Secretary Michael Fallon said Friday, after a visit to the country.

Mosul has been held by Islamic State jihadists since June 2014 and British jets are part of a US-led coalition flying missions against them in Iraq and Syria.

"Though Mosul is a large and complex city, it will fall and will fall soon. I expect the operation for its encirclement to begin in the next few weeks," Fallon said in London following a three-day trip to Iraq.

He added that Iraqi forces were moving into a tactical assembly area in preparation for the assault.

"We ought to be able to get Daesh (another term for the IS group) out of Iraq over the next few months -- the remaining months of this year and next year," Fallon added.

Top US military officers have hinted that the final push for Mosul could begin next month, but there are still significant military, political and humanitarian obstacles between the launch of the operation and entering and retaking the city. 

The drive will involve Iraqi soldiers and police, pro-government paramilitaries and Kurdish peshmerga fighters -- forces that in some cases have not operated together before and do not have unified command structures.

The United Nations says that up to one million people may be displaced by the fighting.

Source: AFP