Graphic video footage has surfaced that appears to show rebel fighters beheading a Catholic priest in the grounds of a monastery in Idlib, northern Syria.
The Vatican has confirmed that François Murad, a 49-year-old Franciscan father, was murdered when jihadist forces believed to be linked to al-Qaida stormed the monastery where he had taken refuge in Gassanieh.
According to reports, fighters loyal to the radical Jubhat al-Nusra front attacked the Convent of the Custody of the Holy Land on Sunday 23 June.
"The Syrian priest François Murad was killed in in the convent of the Custody of the Holy Land where he had taken refuge," Vatican news agency Fides reported.
"This is confirmed by a statement of the Custos of the Holy Land sent to Fides Agency. The circumstances of the death are not fully understood."
Footage purportedly shot in the immediate aftermath of the assault shows a man, believed to be Murad, bound up and blindfolded along with two others as an armed mob of about 100 fighters gathers about them, filming on their mobile phones.
Dozens of men and boys are seen cheering as the captives are executed by a hooded figure holding what appears to be a kitchen knife. In macabre images, the severed heads are then set atop the bodies.
Speaking broken or heavily accented Arabic with a foreign accent, the fighters are captured on film declaring that they are applying the law of God. The mob then breaks into frenzied chants of Allahu Akbar as men close in, jostling to photograph the bodies.
"Franciscan Friar Francois Murad was martyred by Syrian jihadists on June 23," Catholic Online reported, describing the incident as a "death by beheading".
It added: "According to local sources, the monastery where Father Murad was staying was attacked by militants linked to the jihadi group Jabhat al-Nusra."
Father Murad had been tasked with setting up a monastery in Gassanieh, but was forced to abandon the site when it came under heavy fire from rebel positions. He subsequently found shelter at the nearby Convent of the Custody when it was overrun by militia forces, Fides reported.
"After the start of the civil war, the monastery of St Simon Stylites had been bombed and Father Murad had moved to the Convent of the Custody for safety reasons, and to give support to the remaining few, along with nuns of the rosary.
"Father Francois had taken the first steps in the religious life with the Franciscan Friars of the Custody of the Holy Land, and with them he continued to share close bonds of spiritual friendship. After being ordained a priest he had started the construction of a coenobitic [communal] monastery dedicated to St Simon in the village of Gassanieh."
Vatican Radio reported that the majority Christian village of Gassanieh had been under attack by Islamist fighters for weeks, forcing most of the population to evacuate.
"Father Mourad was just one of the many religious men and women putting their faith on the front line in Syria, refusing to abandon the communities they serve, Christian and Muslim," it said.
"They stay because they want to be a sign of hope, light and comfort to people in the midst of destruction."
Archbishop Jacques Behnan Hindo, of the Syrian Catholic church, said he had received messages from Father Murad describing how dangerous the situation had become.
"Lately, Father Francois had sent me some messages that clearly showed how conscious he was of living in a dangerous situation, and offered his life for peace in Syria and around the world," he said.
Pierbattista Pizzaballa, of the Custos of the Holy Land, said: "Unfortunately Syria has now become a battleground not only between Syrian forces, but also between Arab countries and the international community.
"The world must know that the support of gunmen by the West is helping extremists in killing Syrians. With such stances, not a single Christian will remain in the East.
"Those paying the price are the poor, the young and the Christians. The international community must put a stop to all this."