Iraqi forces battled jihadists in west Mosul Sunday, aiming to build a floating bridge across the Tigris to establish an important supply route linked to the recaptured east bank. A week into a major push on the western side of the city, where an estimated 2,000 holdout jihadists and 750,000 civilians are trapped, government forces made steady progress.

But after relatively easy gains on the city's outskirts, they encountered increasingly stiff resistance from the Islamic State group (IS) defending its emblematic stronghold.

"We had an important operation this morning to move towards the bridge," Colonel Falah al-Wabdan, from the interior ministry's Rapid Response units that have spearheaded the breach into west Mosul, told AFP in the Jawsaq neighbourhood.

"We have moved past a large berm constructed by Daesh (IS) with tunnels underneath," he said, adding that the area was heavily mined and that his forces had killed 44 jihadists on Sunday alone.

Wabdan was referring to what is known as "the fourth bridge", the southernmost of five bridges - all of which are damaged and unusable - across the Tigris River that divides the northern Iraqi city.

Government forces retook the east bank from IS a month ago, completing a key phase in an offensive on Mosul that began on October 17 and has involved tens of thousands of fighters.

Wabdan said that securing the bank area near the fourth bridge would allow engineering units to extend a ribbon bridge to the other side and further pile pressure on the jihadists.

"It is very important because if we take it, engineering units... will be able to throw a bridge across from the left bank so we can move supplies and ammunition from the battle field," he said.

Bridging operations under fire are complex and perilous, but Iraqi forces have been trained by the US military and successfully used that strategy before in the fight against IS.

A ribbon bridge assembled with US assistance over the Euphrates River was considered a turning point in the battle that eventually saw Iraqi forces retake the western stronghold of Ramadi from the jihadists a year ago.

Rapid Response was confident it could reach the bridge on Sunday but IS was fighting back, killing at least three government fighters, according to Phil Suarez, who heads operations for NYC Medics, an NGO providing trauma care south of Mosul.

The elite Counter-Terrorism Service that has done most of the fighting against IS in Mosul so far entered the western neighbourhood of Al-Maamun on Friday.

Troops from the US-led coalition assisting Iraq in its efforts to claw back the swathes of territory it lost to IS in 2014 have stepped up their involvement on the ground in recent weeks.

Copyright Agence France-Presse, 2017