Cairo: At least 464 people were executed by the Islamic State (IS) terrorist group from April 28 to May 28 in Syria, according to the Syrian Observatory for Human Rights (SOHR).
The NGO said in a statement on Thursday that half of the murders were reported in the city of Palmyra.
Among those executed were 149 civilians, including 14 children and 13 women, according to the SOHR, which also reported that 67 civilians were killed in Palmyra.
Palmyra, an oasis in the Syrian desert, was a leading cultural centre in the 1st and 2nd centuries AD, and later became an important stop for Silk Road caravans.
Syrian authorities, meanwhile, reported a much higher toll, saying that IS beheaded at least 400 people -- mostly women, children, and elderly -- in Palmyra alone since May 20, after the group gained control of the historic area.
The recent executions bring the total number of killings to 2,618 since the militant group declared a caliphate in late June 2014 in areas under its control in Syria and Iraq.