The chief of Syria's antiquities department, Maamoun Abdelkarim, confirmed the destruction of the tombs on Friday.

"They blew up three tower tombs, the best preserved and most beautiful," Abdelkarim said.

"We received reports 10 days ago but we've just confirmed the news," he added.

Among the three tombs was the Tower of Elahbel. Built in 103 A.D., the tower had four storeys, as well as an underground floor and could purportedly hold to 300 sarcophagi.

Abdelkarim said IS militants had also blown up two temples at the Roman-era, UNESCO World Heritage site.

Demolitions a 'war crime'

The reports on Friday came just days after satellite images from the United Nations (UN) confirmed fears of irreparable damage to Palmyra's Temple of Bel. The cultural agency UNESCO condemned the site's destruction as a war crime.

IS captured Palmyra in May, sparking concerns that militants would destroy the UNESCO World Heritage site, causing destruction similar to what has already been seen at several ancient sites in neighboring Iraq.

Jihadi militants have since published photos and video footage online, purportedly showing the demolition of Palmyra's architecture.

IS considers the buildings or any pagan artifacts as sacriligeous and an affront to its interpretation of Islam.

ksb/kms (Reuters, AFP)