The Islamic State's destruction of Palmyra's ancient temple of Baalshamin is a war crime, the UN's cultural agency has said.
The Temple of Baal Shamin in the ancient oasis city of Palmyra in 2014. Photo: AFP
Syrian officials and activists reported on Sunday that Islamic State (IS) militants had blown up the temple.
In a statement, Unesco said it was "an immense loss for the Syrian people and for humanity".
IS took control of Palmyra in May, sparking fears for the site, considered one of the ancient world's most important cultural centres.
Syria's head of antiquities Maamoun Abdulkarim was quoted as saying the temple was blown up on Sunday, causing "much damage". The UK-based Syrian Observatory for Human Rights (SOHR) reported that it happened a month ago.
The ancient city - which is a Unesco World Heritage site - is famed for its well-preserved Greco-Roman ruins, and the Baalshamin temple, built nearly 2,000 years ago, is one of the city's best-known buildings.
"The systematic destruction of cultural symbols embodying Syrian cultural diversity reveals the true intent of such attacks, which is to deprive the Syrian people of its knowledge, its identity and history," Unesco Director-General Irina Bokova said.
Ms Bokova said those responsible "must be accountable for their actions".
The Islamic State group has destroyed several ancient sites in Iraq, which Unesco has also said was a war crime and an act of "cultural cleansing".
The militants believe any shrines or statues implying the existence of another deity are sacrilege and idolatry, and should be destroyed.
Emma Loosley, a professor at Exeter University who lived near the ancient city for three years, said the temple's cella (inner area) was "pretty much perfect".
"I can't think of another temple as beautifully preserved as the temple of Baalshamin, and what was special about Palmyra was that it was a unique culture," she told the BBC.
"It had its own gods, its own form of art and architecture that you don't get anywhere else."
A week ago, it emerged that the archaeologist who had looked after Palmyra's ruins for four decades, Khaled al-Asaad, had been beheaded by the militant group.
Mr Abdulkarim said the 81-year-old had refused to tell IS where some treasures had been hidden, in an effort to save them.
The modern city of Palmyra - known locally as Tadmur - is situated in a strategically important area on the road between the Syrian capital, Damascus, and the eastern city of Deir al-Zour.
- BBC