Damascus (AFP) - Islamic State group jihadists have blown up several of ancient Palmyra's famed tower tombs as they press their demolition of the UNESCO-listed world heritage site, Syria's antiquities chief said Friday.
IS has carried out a sustained campaign of destruction against heritage sites in areas under its control in Syria and Iraq, and in mid-August beheaded the 82-year-old former antiquities chief in Palmyra.
News of the demolition of the tower tombs which date to the first century AD comes after the jihadists' destruction of the ancient shrine of Baal Shamin and the 2,000-year-old Temple of Bel, regarded as Palmyra's masterpiece.
Antiquities director Maamun Abdulkarim told AFP that among at least seven tombs destroyed were the three best preserved and most treasured funerary towers, including the famed Tower of Elahbel.
"We received reports 10 days ago but we've just confirmed the news," he said.
"We obtained satellite images from the US-based Syrian Heritage Initiative, taken on September 2."
All of Palmyra, including the four cemeteries outside the walls of the ancient city, has been a UNESCO world heritage site since 1980.
In its listing, the UN agency singles out the tower tombs as the "oldest and most distinctive" of Palmyra's funerary monuments -- "tall multi-storey sandstone buildings belonging to the richest families".
- Symbols of economic prosperity -
"On the fronts of those that survive, foremost among them the Tower of Elahbel, there is an arch with sarcophagus halfway up, which in ancient times supported a reclining statue," it says.
"Corridors and rooms were subdivided by vertical bays of loculi (niches for the dead) closed by slabs of stone carved with the image of the deceased and painted in lively colours."
Abdulkarim said the Tower of Jambalik, built in 83 AD, was also destroyed, along with the Tower of Ketout built in 44 AD and famed for vivid scenes etched into its walls.
He said the tower tombs were symbols of the economic boom of Palmyra in the first century AD, when it dominated the caravan trade between east and west from its oasis in the desert.
Some of Palmyra's monuments still remain intact, including its grand amphitheatre and the Temple of Nabu.
- IS pledges further destruction -
The amphitheatre has instead been exploited by IS to parade its brutal version of Islamic justice since it captured the city in May.
In one macabre display, child recruits executed 25 Syrian soldiers on the stage.
According to the Syrian Observatory for Human Rights monitoring group, IS addressed a letter to Palmyra's residents promising further destruction.
"It pledged to demolish and destroy more heritage, saying that 'everything that is worshipped without God will be destroyed'," the Observatory said.
Gruesome violence and the destruction of priceless artefacts have become hallmarks of IS as it has expanded its so-called caliphate straddling Iraq and Syria.
The Sunni extremist group considers pre-Islamic monuments, tombs and statues to be idolatrous and worthy of destruction.
But experts say that while the jihadists prize the shock value of demolishing ancient sites, they are also keen to preserve some artefacts to sell on the black market to fund their "caliphate".
According to Cheikhmous Ali of the Association for the Protection of Syrian Archaeology, upwards of 900 monuments and archaeological sites have been damaged or destroyed during more than four years of civil war.
The destruction of the tower tombs "is an indication of the failure of the international community and global institutions to intervene and solve the situation in Syria," he said.
"It's a continuation of the tragedy of destruction that Syrian heritage has been witnessing for four years."
In addition to damaging sites in Syria, IS has also carried out widespread destruction in neighbouring Iraq, demolishing statues, shrines and manuscripts in second city Mosul, and razing the ancient Assyrian city of Nimrud.