More than 70 people were executed in a fresh massacre in the northern Syrian city of Aleppo, as violence continues to escalate throughout the country.

Opposition groups have claimed that at least 71 bodies were found near a river in the western Bustan al-Qasr district of Aleppo. Lakhdar Brahimi, the UN special envoy to Syria, said that the latest massacre is a sign that the conflict has reached “unprecedented levels of horror”.

According to reports from local activists, most of the dead had been executed with their hands tied behind their back. According to the UN, more than 60,000 people have been killed since the protests against President Bashar al-Assad’s rule began in March 2011.