The temple of Baalshamin in Palmyra in this 1960 archival photo.

ISIS militants have destroyed the ruins of an ancient temple in the Unesco World Heritage city of Palmyra in Syria, officials and activists said Sunday, in another incidence of the extremists desecrating relics from history in the name of religion.

Described by Unesco as an “oasis in the Syrian desert,” the World Heritage site of Palmyra features spectacular ruins that were once a “great city that was one of the most important cultural centers of the ancient world.”

However, ISIS fighters seized the city ruins in May and set to work selling off some antiquities on the black market, while destroying other idols and sites that the group believes go against their version of Islam.

The Syrian Observatory for Human Rights, a British-based monitoring group, said Sunday that the ruins of the Baalshemin temple were blown up by the extremists one month ago.

However, Syrian antiquities chief Maamoun Abdulkarim told Agence France-Presse the destruction occurred on Sunday.

"Daesh placed a large quantity of explosives in the temple of Baal Shamin today and then blew it up, causing much damage to the temple," he told AFP, using another name for ISIS.

"The cella [inner area of the temple] was destroyed and the columns around collapsed," he said.

ISIS militants last week beheaded one of Syria's top antiquities scholars, Khaled al-Asaad, who had worked in Palmyra for more than half a century.

“We know that we will shock the world when they wake up and hear the news [of the scholar's death],” one ISIS militant told BuzzFeed News.

