Isis destroys two historic shrines at ancient city of Palmyra

Mohammed bin Ali's tomb is destroyed

Two shrines at the ancient Syrian city of Palmyra have been blown up by Islamic State militants.

The tombs, which are hundreds of years old, and are thought to be the final resting places of Abu Behaeddine and Mohammed bin Ali, a descendant of the Prophet Mohammed's cousin, were destroyed for being "landmarks of polytheism".

Before-and-after pictures released on Isis social media show militants carrying explosives and the structures - which are not part of the city's famed ancient Roman monuments - in ruins.

The Syrian Observatory for Human Rights, a British-based monitoring group, has previously claimed that Isis had laid mines in Palmyra, but that it was not clear whether it was preparing to destroy the site or deter government forces from advancing towards it.

A militant carries explosives

Syrian antiquities chief Abdul Maamoun Abdulkarim said: "In all the areas where they spread when they see tombs they destroy them as see them as sacrilegious and a return to paganism."

Hundreds of statues had been moved from the city to safe locations, before the militants, who control large swathes of Iraq and Syria, took over, he told Reuters.

A militant plants explosives

The group is notorious for destroying shrines across captured territory in Iraq and Syria.

Video emerged in April of the group apparently destroying artefacts at Nimrud, while another from February showed a museum in Mosul being pillaged.

Palmyra, meanwhile, remains threatened. A 2,000-year-old Unesco World Heritage site, it contains some of the best-preserved Roman-era ruins in the world.