Videos apparently showing rebels killing supporters of Syrian President Bashar al-Assad in Aleppo prove that both sides in the conflict violate human rights, according to Russia's Deputy Foreign Minister Gennady Gatilov.
In what is a huge blow to Syria's President Assad, his most senior diplomat in the UK has quit his post.
Khaled al-Ayoubi, the Syrian charge d'affaires in London, told British authorities he was "no longer willing" to represent his government, because of its "violent and oppressive actions."
He is currently staying at what is is being described as a safe location in the UK.
It is the latest in a string of high profile defections to hit President Assad. Our Senior Political Correspondent Chris Ship reports on this story.
This is a revolution reliant on bravery and bravado and often not much else. This is a brutal fight to the death.
Rebel fighters in Aleppo seem barely able to believe the scale of their own victory, but look likely to be vastly outnumbered very soon.