The Islamic State of Iraq and the Levant (ISIL) group has demolished a monastery founded more than 1,500 years ago in the central Syrian province of Homs, close to where it abducted scores of Christians earlier this month, according to activists and a Christian priest.
The destruction of the Saint Elian Monastery near the town of Qaryatain comes days after ISIL fighters in the city of Palmyra publicly beheaded a respected antiquities scholar who had dedicated his life to studying and overseeing Palmyra's iconic ancient ruins.
The developments have stirred concerns that ISIL may be accelerating its campaign to destroy and loot heritage sites inside the areas of Iraq and Syria the group controls.
"I think we are worried about almost all the heritage sites in Syria. Nothing is safe," Irina Bokova, director-general of UNESCO, told the Associated Press news agency.
Bokova said that ISIL's "view on culture and heritage is just the opposite of what UNESCO stands for".
ISIL, which captured the Qaryatain area in early August, posted photos on social media on Friday that showed bulldozers destroying the Saint Elian Monastery.
A Christian clergyman told AP in Damascus that ISIL members wrecked a church inside the monastery that dates back to the 5th century.
The Britain-based Syrian Observatory for Human Rights, which tracks Syria's conflict, also reported the destruction of the monastery.
A Qaryatain resident who recently fled to Damascus, also told AP that ISIL members had levelled the shrine and removed the church bells.
On Tuesday, Khaled Asaad, a respected 82-year-old scholar who worked for 50 years as head of antiquities in Palmyra, was beheaded, seemingly after ISIL failed to extract information on the whereabouts of hidden artefacts.
In July, ISIL destroyed a famous statue of a lion outside Palmyra's museum, after taking over and looting the ancient city, known as Tadmur in Arabic.
Earlier this month in Qaryatain, ISIL abducted at least 230 people, including 60 Christians from a church, after capturing the town after heavy fighting with the Syrian army, the Syrian Observatory said.
Qaryatain is near a road linking Palmyra to the Qalamoun mountains, along the border with Lebanon.
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ISIL has previously claimed responsibility for destroying shrines - Christian and Muslim - as well as churches. It has vowed to rid territory it controls in Syria and Iraq of symbols of what it calls idolatry.
Elsewhere in Syria, 15 people have been killed in government air raids over eastern Aleppo.
Medical sources have told Al Jazeera the planes targeted Al Bab, a town in the Aleppo countryside that has been under ISIL control and is a regular target.
Opposition activists say the Syrian government is deliberately targeting civilian neighbourhoods.
Source: Al Jazeera And AP