The UN cultural agency called the destruction of the temple, part of a sprawling Roman-era complex that was once among the most popular tourist sites in the Middle East, an "immense loss for the Syrian people and for humanity."
Kishore Rao, Director of the UNESCO World Heritage Centre, said the ancient oasis city of Palmyra sat at a crossroads between the Roman empire, Persia, China and India, and that its soaring architecture was a "masterpiece of human creative genius."
Activists outside Palmyra reported the demolition of the Temple of Baalshamin late yesterday, but there were conflicting accounts of the timing and the extent of the destruction.
The witness, who goes by the name Nasser al-Thaer, said the bombing took place yesterday shortly after 4 PM (local time). The militants had lined the inner and outer walls of the temple with small bottles of explosives more than a month ago, he said.
More From This Section
"I went to see it, not from very close because IS (militants) were there and because I was worried for myself and afraid they will ask me what are you doing here. So I saw it from a distance," al-Thaer told the AP.
He said he feared other ancient sites in Palmyra might be next, but that no explosives have been placed around them.
An IS operative confirmed the temple was destroyed and said a statement would be issued soon. He spoke to the AP over Skype on condition of anonymity because members of the group are not allowed to speak to media.
The extremist group, which has imposed a violent interpretation of Islamic law across its self-declared caliphate straddling Syria and Iraq, claims ancient relics promote idolatry. But the IS group is also believed to sell looted antiquities.
He is currently a member of the Association for the Protection of Syrian Archaeology, which documents the looting and destruction of historic sites.
The temple was extensively refurbished by a wealthy resident of the city, and most of the structure destroyed yesterday dated back to AD 130, he said in an interview from Paris.