Death by explosive necklace, rocket launcher, or obliterated at sea: ISIS release a series of sickening execution videos from war-torn Yemen filmed in just 24 hours!!!!

Slaughter: ISIS has released a series of execution videos in Yemen where four groups of rebels are slaughtered in different sickening scenarios, including having mortar shells tied around their necks.

ISIS has released a series of depraved execution videos from Yemen whose ongoing sectarian war has allowed the terror group to spread its tentacles into the country.

Four videos show Houthi rebels, who are battling both the government and al-Qaeda in the Arabian Peninsula (AQAP), being executed in different sickening scenarios in a desert location.

Six men were blown up by a rocket launcher, another six were put on a boat which was sent out to sea and exploded, four were obliterated by the mortar shells hung around their necks and nine were beheaded with sharp daggers.

Explosion: One video, shared by an ISIS supporter, shows the men being obliterated when the mortar shells around their necks are detonated.

In one video, four men in orange jumpsuits stand with mortar shells tied around their necks like lanyards.

A deafening blast then sends huge amounts of soil and rock into the air. As the dust settles, the men's destroyed, charred bodies can be made seen.

In another of the group's gruesome propaganda videos, a group of men are led single file onto a boat which is then pushed out to sea.

As they sit there, shackled and helpless, the boat and the men on board are blown up remotely.

Six men were killed when a remotely triggered rocket launcher fired a grenade at them, as they sate on the side of a rocky hill.

Nine more were led to a deserted outpost somewhere in Yemen, their hands tied behind their backs, and beheaded by masked ISIS soldiers.

Barbaric: In another sickening execution video, six men sitting on a rocky hill were blown up by a rocket launcher.

Fanatic: A remotely fired rocket launcher is fired at the men in the desert location as the black flag used by jihadi groups including ISIS stands in the foreground

The videos, all shared by ISIS supporters today, come a day after the UK's first airstrikes on Syria, where ISIS controls large swathes of territory.

ISIS, who also have territory in Iraq and Libya, have been able to spread to Yemen in the midst of its own civil war.

Last month, the terror group claimed to be behind the synchronised attacks that killed at least 15 and wounded 30 at checkpoints manned by troops loyal to Yemen's internationally recognised government.

The Houthis are a Sunni Muslim group that has been battling AQAP. ISIS, who claim to be a Sunni group, see them as 'apostates' - or those who have abandoned Islam.

Attacks by pro-ISIS groups intensified in October after they pledged allegiance to the group's leader Abu Bakr al-Baghdadi.

These extremist groups were said to be operating out of the capital Sana'a and other cities along the country's south and south-east.