Damascus: The Islamic State group on Friday kept up a counteroffensive that has rocked US strategy, seizing a key border crossing after capturing an Iraqi provincial capital and a renowned Syrian heritage site.
The jihadists, who now control roughly half of Syria, reinforced their self-declared transfrontier "caliphate" with the capture of the Al-Tanaf to Al-Walid crossing on the Damascus-Baghdad highway.
It was the last border crossing with Iraq still held by the Damascus government. Except for a short section of frontier in the north under Kurdish control, all the rest are now held by IS.
The jihadist surge, which has also seen them capture Anbar capital Ramadi and the ancient Syrian city of Palmyra in the past week, comes despite eight months of US-led air strikes aimed at pushing them back.
It has sparked an exodus of tens of thousands of fearful civilians in both countries and raised fears that the jihadists will repeat at Palmyra the destruction they have already wreaked at ancient sites in Iraq.
President Barack Obama played down the IS advance as a tactical setback and denied the US-led coalition was "losing" to IS.
But French President Francois Hollande said the world must act to stop the extremists and save Palmyra.
UNESCO chief Irina Bokova called the 1st and 2nd Century ruins "the birthplace of human civilisation", adding: "It belongs to the whole of humanity and I think everyone today should be worried about what is happening."
As the jihadists fanned out across Palmyra yesterday, they went door to door executing suspected loyalists of the Damascus government, the Syrian Observatory for Human Rights said.
At least 17 people were killed, the Britain-based monitoring group said.
Syrian state media said loyalist troops withdrew after "a large number of IS terrorists entered the city," which lies at a strategic crossroads between Damascus and the Iraqi border to the east.
IS proclaimed Palmyra's capture online and posted video and stills footage of its fighters in the city's air base and prison, long notorious for its detention of regime opponents.
The jihadists did not immediately post pictures of the UNESCO-listed world heritage site with its colonnaded streets, elaborately decorated tombs and temples.
IS sparked international outrage this year when it blew up the ancient Assyrian city of Nimrud in northern Iraq.
Syria's antiquities director Mamoun Abdulkarim said he feared a similar fate awaits Palmyra, and urged the world to "mobilise" to save it.
IS now controls "more than 95,000 square kilometres (38,000 square miles) in Syria, which is 50 per cent of the country's territory," the Observatory said.
