Unverified video uploaded to Social Media on Thursday appeared to show the Islamic State militant group in control of the Syrian city of Palmyra.
More than a third of its inhabitants have fled, leaving large parts of the city a virtual ghost town.
Seizing Palmyra gives jihadists access to modern army installations and control of a desert highway linking Damascus and Homs with the east of the country.
ISIL militants now control more than half of Syria, according to the UK-based monitoring group the Syrian Observatory for Human Rights.
They seized a border control close to Palmyra.
Fears are growing that historic buildings in the city will be destroyed in the same way ISIL militants targeted antiquities and monuments in Iraq.
Several Roman-era ruins are now believed to be threatened.