Syria's opposition National Council on Monday condemned "in the strongest terms" the murder of a Dutch priest known for his love of Syria in the country's central city of Homs.
"It is with great shock and sorrow that we learned of the assassination of Father Frans van der Lugt in Homs today," National Council president Ahmad Jarba's office said in a statement.
"We condemn in the strongest terms this senseless criminal act and mourn his untimely death," it added.
"We strongly support the united quest of all Syrian opposition groups to find the criminals who perpetrated this cowardly act and to hold them accountable."
Van der Lugt was murdered by an unknown gunman on Monday morning, after living in Syria for nearly five decades and gaining renown for refusing to abandon Homs during a gruelling regime siege.
The statement said van der Lugt was being protected by the Free Syrian Army and his FSA guard was "wounded in the chest this morning when the masked gunman stormed the monastery."
Jarba's spokesman Monzer Akbik said the regime of Syrian President Bashar al-Assad was "ultimately responsible for this crime, as the only beneficiary of Father Frans's death."
"Here was a Christian priest, under the protection of the Free Syrian Army, cowardly assassinated because of his support for the Syrian people," he said.
He said the FSA's commitment to protecting Christians is "well-known," adding: "We lift our united voices in condemning this barbaric act."