Iraq - by the Daily Mail - The terror group has launched a brutal crackdown on militants trying to flee from the battlefield - especially in northern Iraq near its stronghold of Mosul.
Reports have surfaced that a group of fighters had their hands and feet tied up before being bundled into a car where they were gassed to death.
The American Herald Tribune quoted Arabic-language websites as saying: ISIS tied up hands and feet of its militants, put them inside a closed-door car with all the windows rolled up and opened gas hose sent into the car until they died.
It comes after a mass grave was discovered containing the bodies of 200 ISIS terrorists in Iraqs Anbar province. The grave was found on Khalediya Island.
Meanwhile Iraqi forces are preparing to attack ISIS in its de facto capital of Mosul - and residents inside the city and others who have managed to escape have expressed relief at the prospect their home could be liberated from the extremist groups brutal rule.
The Iraqi army and its elite units that will lead the offensive are gradually taking up positions around the city 248 miles north of Baghdad, from whose Grand Mosque in 2014 ISIS leader Abu Bakr al-Baghdadi declared a caliphate spanning regions of Iraq and Syria.
The offensive is slated for late September, said Hisham al-Hashimi, who works for the government as a consultant on ISIS affairs and is author of the book The World of Daesh.
With a population at one time as large as two million, Mosul is the largest urban centre under the ultra-hardline militants control. Its fall would mark their effective defeat in Iraq, according to Prime Minister Haider al-Abadi.
Many ISIS leaders have fled Mosul for Syria with their families ahead of the planned offensive, Iraqs defense minister Khaled al-Obeidi said on July 30.
As Iraqi forces tighten the noose, the militants have grown increasingly paranoid, residents said.
The militants have always kept tight control on communication to preempt hostile propaganda and prevent informants from passing on information to the Iraqi forces or the U.S.-led anti-ISIS military coalition that is carrying out most of the airstrikes on their positions.
They blocked mobile networks in 2014 and banned satellite TV earlier this year, allowing home internet access only through a server they controlled.
As of a month ago they restricted internet access further to a handful of official Wifi centers manned by supervisors who monitor content over users shoulders.
At checkpoints set up by the ISIS amniya, or security committee, people are asked if they have Facebook and must unlock their phones to prove that they do not.