More than 400,000 people have been displaced from western Mosul about two months into the Iraqi army's battle against the Islamic State of Iraq and the Levant (ISIL), according to the UN.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said, citing the Iraqi government, that 434,775 people have fled ISIL's last stronghold in Iraq since Iraqi forces launched the western Mosul operation on February 19.

This brings the number of internally displaced people, since the Mosul operation started in October, to a total of 615,150 Iraqis.

According to OCHA, about 30,000 civilians have returned to their homes in western Mosul since the end of April - meaning that the number of internally displaced people from western Mosul stands at 403,490 people.

The UN Refugee Agency, the UNHCR, announced on Tuesday the opening of a new camp in eastern Mosul for citizens displaced from the west.

The Hasansham U2 camp has a capacity of 9,000.

In recent months, ISIL, also known as ISIS, has stepped up its attacks in different parts of Iraq, apparently in an effort to distract attention from the ongoing US-backed campaign to remove it from Mosul in northern Iraq.

Eastern Mosul was cleared of ISIL fighters in January.

Major offensive

On February 19, Iraqi forces started a major offensive to wrest back the western section of Mosul from ISIL, almost a month after they recaptured the eastern part of the city.

The western side of Mosul is thought to be the most difficult to retake in the ongoing campaign because of the high population density there.

ISIL seized Mosul, Iraq's second-largest city, in a blitz in mid-2014.

READ MORE: Mosul civilians - 'Who knows who was shooting?'

As hundreds of thousands of civilians are still in Mosul, anti-ISIL forces have had to limit their use of aerial attacks and artillery in the city.

Nevertheless, hundreds of civilians have been killed by coalition air raids and shelling, as well as in the counterattacks launched by ISIL.

The US-led coalition bombing ISIL positions in Iraq admitted that it carried out air raids in March at a location in west Mosul where officials and residents say scores of civilians were killed.

According to Iraq's authorities, ISIL now controls less than 7 percent of Iraq.