A Palestinian Authority official denounced Hamas Saturday for its executions in Gaza Friday of 18 suspected collaborators with Israel, calling the killings “cold-blooded murders.”

Hamas was reported Saturday to have executed another four alleged collaborators in the Jabaliya refugee camp, in the northern Gaza Strip

Tayeb Abdel Rahim, the PA president’s secretary-general, said the executions are reminiscent of actions conducted by extreme Islamist groups such as the Islamic State, which has taken over large areas in northern Iraq and Syria.

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Prime Minister Benjamin Netanyahu on Saturday once again compared Hamas to the Islamic State as well, adding that the Gaza-based terror organization was committing war crimes and using civilians as human shields.

“The world saw yesterday [when Hamas killed 18 suspected “collaborators” with Israel] that Hamas, like the Islamic State, carries out mass public executions,” Netanyahu said during a phone call with UN Secretary General Ban-Ki Moon. “In addition, Hamas, like the Islamic State, persecutes and oppresses minorities,” the prime minister continued.

“The ideology of these two groups calls for Islamic caliphates and both use the same murderous methods — Hamas is the Islamic State, the Islamic State is Hamas.”

Netanyahu came under fire on Friday when his office posted a controversial tweet that used an image from the graphic beheading video of US journalist James Foley by the Islamic State terrorist group.

The deleted tweet, which has been posted on BuzzFeed, juxtaposed an image, labeled “ISIS,” of Foley with his black-clad executioner with blade in hand alongside a picture, labeled “Hamas,” of a body being dragged through a street behind a motorcycle. The tweet was labeled “Hamas is ISIS. ISIS is Hamas,” repeating a statement made on Wednesday by Netanyahu.

Later Friday, the office released a similar tweet, this time juxtaposing images of ISIS and Hamas performing public executions.

The simple truth: #Hamas is #ISIS. ISIS is Hamas.

Performing public mass-executions in cold-blood. pic.twitter.com/q7hpTmDq7R — PM of Israel (@IsraeliPM) August 22, 2014

Masked Hamas gunmen on Friday afternoon killed seven suspected informants for Israel near a Gaza City mosque as worshipers were ending midday prayers, following the killing of 11 people earlier in the day, bringing the total number of alleged collaborators killed in the coastal strip on Friday to 18, according to witnesses and Hamas media.

One witness said masked gunmen lined up the seven men in a side street and opened fire on them. He spoke on condition of anonymity, fearing for his own safety.

The executions came on the heels of Thursday’s assassinations of two of Hamas’s most senior terror commanders and another senior member in an Israeli strike. Israel also attempted to assassinate Hamas military chief Muhammad Deif on Tuesday, and his fate is still unknown. Israeli officials have asserted Deif is likely dead, although Hamas claims he survived the strike.

Israel’s intelligence services rely, in part, on informers to pinpoint the whereabouts of Hamas leaders.

Last month, at the height of the Israel Defense Forces’ Operation Protective Edge in the Gaza Strip, a Palestinian media source reported that Hamas had killed over 30 suspected collaborators.

Unnamed Palestinian security sources in Gaza told Palestine Press News Agency at the time that Hamas had apprehend dozens of suspected spies in the northern neighborhood of Shejaiya — which saw heavy fighting with the IDF during July — and summarily executed them following a short investigation. The sources said that many of the suspects were caught with weapons, telephones, and SIM cards from Israeli cell provider Orange.

AP and AFP contributed to this report