CAIRO — In a gruesome replay of beheadings of captive Christians, an Islamic State video disseminated on social media Sunday purportedly shows the point-blank shootings and decapitations of two groups of Ethiopian Christians in Libya.

It depicts the killings in what were apparently two locations, one described as being in the country’s south and the other showing a sunny Mediterranean beach. The same English-speaking fighter who presided over similar killings in a video released in February declares, “We are back again.”

The Ethiopian Christians, if their identity is ascertained, join a long list of victims of the Islamic State. In Iraq and Syria, the group has taken particular aim at religious minorities, including Yazidis and Assyrians, while enforcing a more widespread reign of terror with tactics such as public executions, mass abductions and sexual enslavement, together with the destruction of cultural treasures.

The nearly half-hour-long video, carrying the imprint of the militant group’s production arm, Al-Furqan Media, echoed the choreographed savagery of the February one, which showed the simultaneous beheadings of 21 men, 20 of them Egyptian Coptic Christians, on a Libyan beach.

Egypt at the time retaliated with airstrikes and tried without success to marshal regional support for military action against Islamist groups in Libya.

But Egypt is a major military power, whereas Ethiopia’s use of force has mainly been confined to war with its neighbor, Eritrea.

Many of the executed Copts were from the same few wretchedly poor villages in southern Egypt. Impoverished and desperate laborers from nearby countries, including Egypt, Ethiopia and Sudan, continue to seek employment in Libya despite the mortal risks they run merely by being present in the collapsing North African nation. Christians have been at particular peril.

In the new video, released one week after Eastern Rite Christians celebrated Easter, the black-clad apparent ringleader informs “the nation of the cross” that Christians falling under the Islamic State’s control face death if they do not accept Islam, according to a transcript provided by the U.S.-based SITE Intelligence Group, which monitors militant activity.

The killings were carried out to “take revenge for Muslim blood,” the chief executioner said.

“We swear to Allah … you will not have safety, even in your dreams, until you embrace Islam,” he said. “Our battle is a battle between faith and blasphemy.”

The video’s date and locations could not be independently verified, but depictions of previous killings have been authenticated by Western intelligence services.

Libya has fallen into chaos, with an array of heavily armed militias battling for political power and energy wealth. They are organized loosely into two factions loyal to either the Islamist-leaning former parliament or an internationally recognized government based in the country’s east.

Neither has gained the upper hand in months of fighting that has caused tens of thousands of Libyans to flee their homes, and international mediation efforts have failed.

Islamic militant groups across North Africa have declared allegiance to the Sunni Muslim militants of the Islamic State, whose home base lies in a swath of Iraq and Syria.

In Libya, militants identifying themselves as Islamic State loyalists had carried out previous strikes, including the deadly bombing of a luxury hotel in Tripoli in January.