The international community should immediately act to defend the besieged Syrian town of Kobane from the jihadist Islamic State group, the UN's envoy to Syria said on Tuesday.
"The world, all of us, will regret deeply if ISIS (Islamic State) is able to take over a city which has defended itself with courage but is close to not being able to do so. We need to act now," Staffan de Mistura said in a statement.
"The international community needs to defend them. The international community cannot sustain another city falling under ISIS," he insisted.
His comments came as Turkey and analysts warned IS was on the verge of seizing control of the strategic town near the border with Turkey, after a desperate weeks-long defence by Kurdish fighters.
The fall of Kobane, Syria's third-largest Kurdish town, to the IS group would mark a major victory for the extremists, who aim to take control over a long stretch of the border area for their self-proclaimed "Islamic caliphate".
With the battle entering a crucial phase, US and Arab warplanes launched fresh strikes on IS positions near Kobane.
At least 412 people, more than half of them jihadists, have been killed in and around Kobane since mid-September, according to the Syrian Observatory for Human Rights, a Britain-based monitoring group.
But de Mistura insisted the jihadists remained at an unfair advantage.
The Kurdish defenders, he said, were fighting with "normal weapons, whereas the ISIS has got tanks and mortars."
The Kurds in Kobane "have been defending themselves with great courage. But they are now very close to not being able to do so," he stressed.
He hailed Turkey for its humanitarian effort in taking in more than 200,000 inhabitants of Kobane, but stressed that "what is needed now is concrete action."
Without more international assistance, the outcome could be horrifying, he warned.
"The world has seen with its own eyes the images of what happens when a city in Syria or in Iraq is overtaken by the terrorist group called ISIS or Da'esh: massacres, humanitarian tragedies, rapes, horrific violence," de Mistura said.