Mosul, Iraq: Nearly 100,000 people have poured out of west Mosul in less than three weeks, the IOM said Wednesday, as Iraqi forces advance in their battle to retake the area from jihadists.

Iraqi security forces launched a major push last month to recapture west Mosul, the most populated urban area still held by the Islamic State group with an estimated 750,000 residents when the battle began.

Iraqi special forces units and police have made steady progress in the area, forcing IS out of a series of neighbourhoods and retaking important sites such as the airport, Mosul museum, train station and provincial government headquarters.

But the battle for west Mosul -- which is smaller but more densely populated than the eastern side which Iraqi forces recaptured earlier this year -- has pushed a flood of people to flee their homes.

Between February 25 and March 15, more than 97,000 people have been displaced from west Mosul, the International Organization for Migration said on its official Twitter account.

It marks an increase of around 17,000 from the displacement figure the IOM released the previous day, though this does not necessarily indicate that all of those additional people fled in the past 24 hours.

The IOM also said that Iraqi government figures indicated a total of more than 116,000 people from west Mosul had gone through a screening site south of the city.

Men, women and children carrying their possessions sometimes walk for hours before arriving at a security forces checkpoint.

From there they can take buses or pickup trucks to camps after the men go through initial screening aimed at identifying those with IS ties.

Hajj Ahmed, a 55-year-old wearing a dark coat over a traditional robe who had recently fled Mosul, said that people were living under IS siege.

- Advance west of Mosul -

"They have been besieging people for seven days," Hajj Ahmed said, praising Iraq's elite Counter-Terrorism Service for saving them.

"All the buildings have been destroyed over our heads by the car bombs. Some families are still stuck there," he said.

On the military front, Iraq's Joint Operations Command announced that soldiers and pro-government paramilitaries have recaptured the entire Badush area, northwest of Mosul.

It is an area that includes Badush prison, where Iraqi paramilitary forces said they had uncovered a mass grave containing the remains of hundreds of people executed by IS after the jail was recaptured last week.

Both Human Rights Watch and the United Nations have said that the jihadists killed up to 600 inmates at a ravine near the prison.

Iraqi soldiers and members of pro-government paramilitary groups are fighting IS west of Mosul, while CTS and the Rapid Response Division -- a special forces unit operating with members of the federal police -- are spearheading the advance in inside the city.

In Mosul, CTS forces hunted for bombs left by IS on Wednesday in areas that have recently been recaptured.

CTS is conducting an "operation to clear and search for bombs and explosives-rigged cars," Staff Lieutenant General Abdulwahab al-Saadi, one of the top commanders in the unit, told AFP.

"There is not any operation to advance and attack new neighbourhoods in west Mosul today," Saadi said.

Staff Major General Maan al-Saadi, another CTS commander, also confirmed that the focus on Wednesday was on searching and clearing areas that had already been retaken.

IS overran large areas north and west of Baghdad in 2014, but Iraqi forces backed by US-led air strikes have since retaken most of the territory they lost, launching the operation to retake Mosul -- the country's last IS-held city -- in October.