Jihadist militants from Islamic State (IS) have blown up three funerary towers at the ancient city of Palmyra, Syria's antiquities chief has said.
Maamoun Abdul Karim said they included the Tower of Elahbel, built in AD103 and one of the best-preserved.
The multi-storey sandstone monuments, standing outside the city walls in an area known as the Valley of the Tombs, belonged to rich Palmyrene families.
Their demolition comes only days after IS blew up Palmyra's two main temples.
The group, which captured the Unesco World Heritage site from government forces in May, has previously destroyed two Islamic shrines - those of a Shia saint and Sufi scholar - near Palmyra, which they described as "manifestations of polytheism".
The Valley of the Tombs, in the hills to the south and west of the ruins of the Greco-Roman city, contains a series of funerary towers of various sizes.
The towers were divided into compartments, or loculi, into which sarcophagi were placed before being sealed with slabs of stone carved with an image of the deceased and painted in lively colours.
Ancient city of Palmyra
- Unesco World Heritage site
- Site contains monumental ruins of great city, once one of the most important cultural centres of the ancient world
- Art and architecture, from the 1st and 2nd Centuries, combine Greco-Roman techniques with local traditions and Persian influences
- More than 1,000 columns, a Roman aqueduct and a formidable necropolis of more than 500 tombs made up the archaeological site
- More than 150,000 tourists visited Palmyra every year before the Syrian conflict
The Tower of Elahbel was among the most prominent. It was four storeys high and could purportedly accommodate up to 300 sarcophagi.
Mr Abdul Karim told the AFP news agency that he had received reports 10 days ago that the "best preserved and most beautiful" towers had been blown up, but only just confirmed the news.
"We obtained satellite images from the US-based Syrian Heritage Initiative, taken on 2 September," he added.
On Tuesday, satellite images confirmed reports that IS had destroyed the Temple of Bel, which the UN Educational, Scientific, and Cultural Organisation (Unesco) said was one of the most important religious edifices of the 1st Century in the East.
Last month, the jihadist group blew up the smaller Temple of Baalshamin and beheaded the archaeologist who looked after the site for four decades, Khaled al-Asaad, after he reportedly refused to reveal where treasures had been hidden.
Unesco's director-general Irina Bokova has said the systematic destruction of Palmyra constitutes a "war crime" and called on the international community to stand united against IS efforts to "deprive the Syrian people of its knowledge, its identity and history".
IS has ransacked and demolished several similar ancient sites that pre-date Islam in Iraq.
The sale of looted antiquities is nevertheless one of the group's main sources of funding. It has also been accused of destroying ancient sites to gain publicity.
The Syrian authorities removed hundreds of statues and priceless objects before IS overran Palmyra, among them the carved images found in the funerary towers.