The Pentagon announcement came hours after the Iraqi special forces advanced and reached the Tigris River bank in the southeastern part of the city, opposite the airport, Efe news reported on Tuesday.

"IS fighters are surrounded on all sides by a superior force," said Pentagon spokesman Navy Captain Jeff Davis, who explained that the IS group "has no ability to reinforce or resupply".

"We do believe their days there, (particularly) in eastern Mosul, are numbered and they are beginning to realise it," added Davis.

The west of the city, where the airport was located, was still completely controlled by the militants, but the five bridges connecting two sides of the city were half-destroyed by allied bombings, so the fighters in the east were partially isolated.

Davis explained that some of them attempted to "cross the river on foot using planks" and tried to move vehicles across the river, one by one, using a crane.

These advances came after the start of the new phase of the offensive against the IS following the October 2016, launch of a major campaign to retake the last militant stronghold in Iraq.

Troops have managed to seize more than 60 per cent of the eastern side of Mosul and large areas around the city, under IS control since 2014, the report added.