It has now been confirmed that Fr Francois Murad (49) was butchered and his killers apparently used a kitchen knife for the beheading.
According to a report from Catholic Online, Fr Murad was beheaded in northern Syria on June 23 while setting up a monastery in Gassanieh.
Forces from Jabhat al-Nusra – which is fighting in Syria to oust President Bashar Assad – apparently accused Fr Murad of working with the regime.
An extremely graphic video from Live Leak reposted by Catholic Online showed amateur footage of Fr Murad's execution as dozens of spectators chanted.
In the grainy film footage, a man believed to be Fr Murad is first seen sitting with his hands bound before being beheaded with a simple kitchen knife.
Onlookers, chanting "Allahu Akbar" ("God is Great"), can be seen in the footage photographing and capturing the horrific scene.
The statement from the Vatican said that the group had the backing of al-Qaida.
Fr Pierbattista Pizzaballa told the news agency that the monastery of St Anthony, which was "the only safe area" for Fr Murad and several other Christians, was attacked when Fr Murad tried to resist the militants.
He said: "Unfortunately Syria has now become a battleground not only between Syrian forces, but between Arab countries and the international community. And those paying the price are the poor, the young and Christians."