Iraqi security forces have launched an attack on Mosul airport, a key part of the government's offensive to drive so-called Islamic State (IS) militants from the western half of the city.

They also stormed the nearby al-Ghazlani military camp, where fierce clashes were under way, AP reported. The runway has already been destroyed by IS, but seizing such a large site would help the Iraqi army control southern routes into Mosul.

Eastern Mosul was retaken last month. The BBC's Quentin Sommerville, who is embedded with Iraqi federal police units, says they have reached the airport perimeter.

A military spokesman told Iraqia TV that simultaneous raids were being carried out on the airport and al-Ghazlani base to "distract" IS.

"We can confirm that the Mosul airport militarily has fallen and it's a matter of short time to fully control it," Counter-Terrorism Service (CTS) spokesman Sabah al-Numan said. CTS troops and elite Rapid Response troops are carrying out the raids.

The airport and the al-Ghazlani base are on Mosul's southern outskirts on the western side of the Tigris river.

Thousands of Iraqi troops, backed by artillery and air power, are involved in the assault to retake Mosul.

Leaflets warning residents of an imminent offensive were earlier dropped over western Mosul, where military officials say narrow winding streets could make retaking the area particularly difficult.

Although slightly smaller than the east, western Mosul is more densely populated and includes districts seen as pro-IS.

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The UN has voiced concern about the welfare of civilians trapped in the city, amid reports that they could number up to 650,000.

More than 160,000 people have already fled their homes in and around the city.

The UN said in late January that almost half of all the casualties in Mosul were civilians.

All bridges linking the east and west of the city, across the Tigris river, have been destroyed by air strikes.

IS jihadists overran Mosul as they spread across much of northern and western Iraq in 2014.

(Source: BBC)