The Islamic State branch in the Sinai Peninsula on Wednesday called on its supporters to attack Hamas in a gruesome execution video as long-simmering tensions between the rival Islamic terror groups erupted into the open.

The 22-minute long video culminated with the execution of one of its members, shot in the back of the head for allegedly smuggling weapons to Hamas.

“[Hamas] uses its smuggled weapons to empower that which was not revealed by God. It also fights supporters of the Islamic State in Gaza and the Sinai and prevents the migration of these supporters from Gaza to the Sinai,” said a speaker in the video, who is referred to as Abu Kazem al-Maqdisi, an Islamic State preacher in the Sinai, originally from Gaza.

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Maqdisi calls on viewers to attack the security headquarters and courthouses of Hamas in Gaza, as these are “the pillars of tyranny.”

At the end of the video, the narrator declares that a man, named as Musa Abu Zamat, who was once among the ranks of Islamic State, was sentenced to death for “smuggling weapons to the apostates of the Izz a-Din al-Qassam Brigades,” referring to Hamas’s military wing.

The accused is then shot in the back of the head.

The shooter was identified in news reports as Muhammad al-Dajani, a former member of Hamas’s military branch in Gaza.

Dajani’s family released a statement to the press decrying his actions in the video.

Hamas, a terror group sworn to Israel’s destruction, has run Gaza for a decade but have been regularly criticized by more radical jihadist groups in the Strip.

Hamas has arrested dozens of Salafi militants, which continues to a be a source of tension between the two sides.

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The Palestinian terror group that rules Gaza has long been accused by the government in neighboring Egypt of aiding the Islamic State’s insurgency in Egypt’s restive North Sinai region.

In recent months, Hamas has beefed up security along Gaza’s southern border with Egypt seeking to assure Cairo that it is fighting IS sympathizers. The Hamas crackdown on the Egyptian militants was a key part of restoring ties between Hamas and Cairo, which has since played a key role in Palestinian reconciliation agreements.

Hundreds of Egyptian soldiers, police officers and civilians have been killed in fighting the bitter Islamic insurgency in the Sinai. But recently they have also turned their attention to Hamas.

In August, a member of the Islamic State group carried out the first suicide bombing against Hamas forces in Gaza, killing a border guard.

In the 22-minute long video, Islamic State also blamed Hamas for failing to prevent US President Donald Trump’s decision in December to declare Jerusalem as Israel’s capital. The video began with a clip of that announcement from the White House.

Islamic State also slammed Hamas for failing to fight Jews for the right reasons.

The video showed clips of Hamas leaders saying the terror group only fights Jews for occupying Palestinian land, and that the group has no quarrel with the Jewish religion.

The narrator in the video criticized Hamas for not fighting Jews for their “false creed.”

Islamic State, in the video, also criticized Hamas for accepting democratic values by participating in elections with rival Palestinian factions and for being agents of Iran. Hamas has said Iran is currently its biggest military supporter.

On Thursday, Hamas spokesperson Salah Bardawil dismissed the Islamic State video as a “Zionist production.”

The video is “a Zionist production in which Arab tools participate to distort the resistance…This is what the Zionist intelligence agency and its lackeys have been striving for,” he wrote in a statement on Twitter.

Bardawil argued Hamas’s conflict with Salafis is not ideological, but rather an issue of security.