Iraqi security forces have pushed deeper into western Mosul, gaining control of a neighbourhood along the Tigris River and the foot of one of the city's five bridges amid intense clashes with ISIL fighters, according to a senior Iraqi commander.

Thamir al-Hussaini said the troops pushed deeper into Gawsaq on Monday and reached the bridge known locally as the Fourth Bridge.

All of Mosul's bridges spanning the Tigris River and connecting the western part of the city, still held by ISIL, or the Islamic State of Iraq and the Levant group, with its eastern sector, were disabled by air strikes last year.

The western part of Mosul, the country's second-largest city, is the last significant urban area that ISIL holds in Iraq.

Snipers and car bombs

Hussaini told the Associated Press news agency that ISIL, also known as ISIS, was fighting back with snipers, anti-tank missiles and suicide car bombs, and described the clashes as "fierce".

He said Iraqi troops suffered casualties, but did not give a specific number.

He said Iraqi counterterrorism forces moved later on Monday from Gawsaq into the nearby Wadi Hajar neighbourhood.

Al Mayadeen, the Lebanon-based private broadcaster, aired live footage from Gawsaq, showing Iraqi troops in armoured vehicles and Humvees pushing through dusty streets as gunfire echoed.

Thick black smoke was seen billowing from different areas following air strikes.

The advances come after Iraqi forces last week took Mosul's international airport and a large military base next to it before pushing into Mamun, the first neighbourhood in the western half of the city after the airport.

Though incremental and only the beginning of what is expected to be a long and protracted battle for the rest of Mosul, the latest developments reflect the Iraqi military's determination to liberate the city.

Iraqi authorities declared the city's eastern half "fully liberated" from the group in January, three months after launching the operation to take back Mosul.

The city fell to ISIL in the summer of 2014, along with large expanses of northern and western Iraq.