MOSUL (Iraq) • US-backed Iraqi troops expanded their foothold on the eastern side of ISIS' stronghold of Mosul yesterday, as the group pledged to mount more suicide attacks to counter an offensive to take the city.

The elite Counter-Terrorism Service (CTS) stormed the Tahrir district on the north-eastern edge of Mosul, the last major Iraqi city under control of the Sunni hardline Islamic State in Iraq and Syria (ISIS) group.

A Reuters correspondent reporting from the CTS-held line in Tahrir saw civilians streaming out of the nearby Aden district where fighting blazed, pushing trolleys containing their belongings and carrying home-made white flags.

The women were still shrouded in black robes imposed by the militants, but most had uncovered their faces as they fled intense fighting.

Militants have been steadily retreating from areas around Mosul into the city since the battle started on Oct 17, with air and ground support from a United States-led coalition.

"The advance is slow due to the civilians," said CTS Lieutenant-General Abdul Wahab al-Saidi, adding that the US-trained unit aimed to clear the rest of the neighbourhood during the day.

A Friday prayer sermon referring to "mujahideen", or holy war fighters, could be heard coming from a mosque under the control of ISIS in the area.

An armed man, possibly a sniper, was in the minaret of the mosque.

As the offensive entered its second month, Iraqi government forces are still fighting in a dozen of about 50 neighbourhoods on the eastern part of Mosul, which is divided by the Tigris River that runs through its centre.

Militants are dug in among the civilians as a defence tactic to hamper air strikes, moving around the city through tunnels, driving suicide car bombs into advancing troops and hitting them with sniper and mortar fire.

A loud explosion was heard several streets away from the CTS lines. An officer said a suicide bomber had blown himself up after being surrounded in a house.

The CTS unit was using a drone to try to detect insurgents.

The number of fighters who are ready to blow themselves up is increasing, an insurgent commander told ISIS' weekly magazine, al-Nabaa, published online on Thursday.

"We are giving you the good news that the number of brothers ready for martyrdom is very large and, with God's grace, the brothers who are demanding martyr operations are increasing," said the unnamed commander.

The offensive to take Mosul, the largest city under ISIS control in either Iraq or Syria, is turning into the biggest battle in Iraq's turbulent history since the US-led invasion that toppled Saddam Hussein in 2003.

Iraqi military estimates put the number of ISIS fighters in Mosul at 5,000 to 6,000.

Facing them is a 100,000-strong coalition of Iraqi government forces, Kurdish fighters and Shi'ite paramilitary units.

In a twist to the fighting, ISIS is now deploying tanks made of wood. The life-size replicas are intended to confuse air support from the US-led coalition, commanders said.

Although they may look far from realistic when viewed from close quarters, it is harder to tell what they are made of from the sky.

Iraqi forces discovered a building used to manufacture the decoys when they retook the village of Sada, north of Mosul, last week. In addition to three fake tanks, they found five wooden Humvees.

There were even mannequins designed to look like fighters operating machine guns and plastic weapons.

It is the latest in a range of elaborate tactics the militants are using as they try to cling to the city.

REUTERS, WASHINGTON POST