Syrian activists said late Sunday that members of the Islamic State in Iraq and the Levant (ISIL) have destroyed a nearly 2,000-year-old arch in the ancient city of Palmyra, the latest victim in the group's campaign to destroy historic sites across the territory it controls in Iraq and Syria.

The Arch of Triumph was one of the most recognizable sites in Palmyra, which the ISIL group seized in May. The monumental arch sat atop the famed colonnaded streets of the ancient city, which linked the Roman Empire to Persia and the East.

The Britain-based Syrian Observatory for Human Rights said ISIL blew up the arch but left the colonnades in place.

Syria’s antiquities chief, Maamoun Abdulkarim, "It's as though there is a curse that has befallen this city and I expect only news that will shock us. If the city remains in their hands the city is doomed," Abdulkarim said.

“It is now wanton destruction. … Their acts of vengeance are no longer ideologically driven because they are now blowing up buildings with no religious meaning,” he added.

An opposition activist who uses the name Khaled al-Homsi also posted on Twitter late on Sunday that ISIL had destroyed the arch.

Homsi was a nephew of Khaled Asaad, the 81-year-old antiquities scholar and long-time director of the Palmyra site who relatives and witnesses say was beheaded by ISIL in August.

Palmyra's sprawling Roman-era complex, which also includes remains of temples to local gods and goddesses, has been under attack from the ISIL since they seized the site earlier this year.

Palmyra was one of the most important cultural centers of the ancient world, according to cultural agency UNESCO, which has described it as the crossroads of several civilizations. The organization has called such acts war crimes and says Islamic State seeks to wipe out evidence of Syria’s diverse heritage.

ISIL espouses a fiercely purist school of Sunni Islam, deeming many other Muslims to be heretics. Its fighters have destroyed Shia and Sufi religious sites and attacked churches and other shrines in the parts of Syria and Iraq under their control.

ISIL argues Palmyra’s ancient relics promote idolatry and says they are destroying them as part of their purge of paganism.

However, the group is also believed to sell off looted antiquities, bringing in significant sums of cash.

In recent weeks, ISIL blew up two famed temples and tower tombs in Palmyra.

ISIL's targeting of priceless cultural artifacts has sparked global outrage and accusations of war crimes.

UNESCO, the UN heritage agency, has called such destruction an “intolerable crime against civilization.”

Before the outbreak of Syria's war in March 2011, Palmyra's UNESCO heritage site was one of the top tourist attractions in the Middle East.

Al Jazeera with wire services