Islamic State militants beheaded one of Syria's most prominent antiquities scholars in the ancient town of Palmyra, then strapped his body to one of the town's Roman columns, Syrian state media reported on Wednesday.

The killing of 81-year-old Khaled al-Asaad was the latest atrocity perpetrated by the militant group, which has captured a third of both Syria and Iraq. Since IS overran Palmyra in May, there have been fears the extremists, who have destroyed archaeological sites in Iraq, would demolish its 2,000-year-old Roman-era city at the town's edge, one of the Middle East's most spectacular archaeological sites.

According to Syrian state news agency SANA, al-Assad was beheaded on Tuesday in a square outside the town's museum. Local human rights activists said dozens of people gathered to witness the killing. Asaad had been held by IS for about a month, it added.