DAMASCUS - The number of refugees from the conflict in Syria now tops three million, the United Nations said on Friday, as US President Barack Obama admitted he still has no strategy to tackle advancing jihadists.
UN refugee agency chief Antonio Guterres said that Syria now constituted the "biggest humanitarian emergency of our era," after a million people joined the exodus in the past year alone, as fighters of the Islamic State seized swathes of the northeast.
The jihadists have sown panic with a spate of atrocities, executing more than 160 captured Syrian soldiers and an Iraqi Kurdish fighter in the past few days, following its brutal beheading of US journalist James Foley earlier this month.
The scale of the crisis facing the international community was further highlighted by the seizure by rival Islamists led by Al-Qaeda of 43 UN peacekeepers on the Golan Heights.
The militants also surrounded another 75 peacekeepers from the Philippines, triggering a tense standoff for the UN mission that has monitored an armistice between Syrian and Israeli troops on the strategic plateau for decades.
Dampening hopes of imminent air strikes in Syria, Obama said he was still developing a comprehensive plan to defeat IS, which has also overrun large swathes of neighbouring Iraq.
The civil war in Syria has killed some 191,000 people since it erupted in March 2011 with President Bashar al-Assad's bloody effort to put down an uprising.
But it has taken on another dimension as IS jihadists exploited the power vacuum to move in, unleashing a series of atrocities that have shocked the world.
"We don't have a strategy yet," Obama said ahead of a meeting with security chiefs.
But he said he was dispatching Secretary of State John Kerry to the Middle East to build support in the region against IS.
'Message in blood'
Washington has carried out air strikes in neighbouring Iraq that have helped Kurdish forces to claw back some of the territory they lost to a renewed offensive by the jihadists earlier this month.
The Iraqi Kurdish leadership's military cooperation with the United States has infuriated the jihadists who posted grisly video footage on Thursday of their execution of a Kurdish fighter outside a mosque.
The video, titled "A message in blood to the leaders of the American-Kurdish alliance," also shows other captive Kurdish fighters warning that they risk the same fate if the cooperation continues, the SITE Intelligence Group monitoring service said.
The prisoners were paraded in orange jumpsuits of the sort used at the US detention centre in Guantanamo Bay, Cuba where hundreds of jihadists were interned during Washington's "war on terror".
The video comes hot on the heels of footage of scores of bodies heaped in the desert that IS boasted were those of Syrian soldiers it captured and killed following its seizure of a key air base last weekend.