Charge d'Affaires Khaled al-Ayoubi last night informed the Foreign Office of his decision to resign.
Reacting to the resignation, Prime Minister David Cameron said al-Ayoubi was "basically defecting from the Syrian regime," and added: "We want this regime to crumble and fold as fast as possible.
Look what it's doing to its own people in Aleppo.
Absolutely appalling behaviour.
So this is another step on the way to Syria having a proper transition."
A Foreign Office spokesman said today, "Mr al-Ayoubi has told us that he is no longer willing to represent a regime that has committed such violent and oppressive acts against its own people, and is therefore unable to continue in his position".
He added, "Mr al-Ayoubi was the most senior Syrian diplomat serving in London.
His departure is another blow to the Assad regime.
It illustrates the revulsion and despair the regime's actions are provoking amongst Syrians from all walks of life, inside the country and abroad".
Britain, the spokesman added, would urge others around Bashar Al-Assad to follow al-Ayoubi's example and to disassociate themselves from the crimes allegedly being committed against the Syrian people and to support a peaceful and free future for Syria.
