Bokova reminded all parties in Syria's civil war of the country’s obligations under the 1954 Hague Convention for the Protection of Cultural Property, to which Syria is a signatory.

“The reports from Aleppo are deeply distressing,” Bokova said. “The human suffering caused by this situation is already extreme."

That the fighting is now destroying cultural heritage that bears witness to the country’s millenary history — valued and admired the world over — makes it even more tragic. “The Aleppo souks (markets) have been a thriving part of Syria’s economic and social life since the city’s beginnings," Bokova said.

Aleppo has been a cultural crossroads since the second millennium BC.

“Syria is a signatory to the 1954 Hague Convention. As such it is bound to do its utmost to safeguard this heritage from the ravages of war," Bokova said. She added: “I appeal to all forces to do their utmost to spare these monuments to human history that have contributed so much to Syria’s growth and prosperity — and which will undoubtedly prove vital to the country’s reconstruction.

“UNESCO stands ready to provide all of its expertise and support for the safeguarding of Aleppo and all of Syria’s extraordinary cultural heritage and, as soon as security permits, I will send a team there to assess the situation and provide emergency assistance for the protection of this heritage, both in terms of mitigation of this tragedy and prevention of further damage.”

The old city of Aleppo was inscribed on UNESCO’s World Heritage List in 1986, in recognition of its “rare and authentic Arab architectural styles” and its testimony to the city's cultural, social and technological development from the Mamluke period. It is one of six Syrian World Heritage sites.