Men are accused of involvement in the execution of nearly 300 civilians by government forces in Damascus in 2013, which the perpetrators filmed

Authorities in Damascus have arrested three men they claim were involved in a notorious massacre of civilians by Syrian security forces revealed by the Guardian three years ago.

Footage posted online purported to show one of the men, Monzer al-Jazairi, with his hands bound and being led through the heavily damaged streets of Tadamon, the Damascus suburb where nearly 300 people were killed in an atrocity filmed by the perpetrators themselves and then leaked by a whistleblower to activists in Europe.