SURUC (AFP) - Kurdish fighters halted a thrust by extremists from the Islamic State in Iraq and Syria (ISIS) towards the heart of the battleground Syrian town of Kobane Saturday, after the UN warned thousands of civilians risked massacre.
The pre-dawn attack came after the ISIS militants overran the Kurdish headquarters in the border town on Friday, sparking fears they would cut off the last escape route to neighbouring Turkey.
But US officials warned that while world attention is focussed on Kobane, the militants have been piling pressure on government troops in neighbouring Iraq, leaving the army in a "fragile" position in Anbar province between Baghdad and the Syrian border.
The renewed ISIS drive on the centre of Kobane sparked 90 minutes of heavy fighting with the town's Kurdish defenders before the militants fell back, the Syrian Observatory for Human Rights said.
US-led coalition warplanes also carried out two air strikes on ISIS targets south and east of the town early Saturday, according to the Britain-based monitoring group, which has a wide network of sources inside Syria.
US-led warplanes have intensified air strikes against ISIS, which has been attacking Kobane for three weeks, but the Pentagon has said that there are limits to what can be done without troops on the ground.
Small groups of Kurdish fighters were trying to harry the encircling militants with operations across the front line, Observatory director Rami Abdel Rahman told AFP.
UN envoy for Syria Staffan de Mistura warned Friday that 12,000 or so civilians still in or near Kobane, including about 700 mainly elderly people in the town centre, "will most likely be massacred" by ISIS if the town falls.
Kobane was "literally surrounded" except for one narrow entry and exit point to the Turkish border, de Mistura said.
He called on Turkey, "if they can, to support the deterrent actions of the coalition through whatever means from their own territory."
"We would like to appeal to the Turkish authorities in order to allow the flow of volunteers at least, and their equipment to be able to enter the city to contribute to a self-defence operation," he said.
Turkey has been deeply reluctant to allow weapons or Kurdish fighters to cross the border despited repeated nights of protests among its own large Kurdish minority that have left 31 people dead.
The situation is complicated by the close ties between the town's Kurdish defenders and the outlawed Kurdistan Workers Party (PKK), which has waged a three-decade insurgency for self-rule in southeastern Turkey that Ankara is determined not to embolden.
Washington has been frustrated over Ankara's reluctance to commit its well-equipped and well-trained forces to the coalition against ISIS but reported "progress" after two days of talks in Ankara by the coalition's coordinator, retired US general John Allen.
Military chiefs from the 21 countries already committed to the US-led coalition are to meet in Washington next week to discuss strategy, Pentagon officials said.
US defence officials insist the primary focus of the coalition's campaign remains Iraq, where there are capable local forces on the ground to work with, particularly Kurdish forces in the north.
But officials voiced concern about the "tenuous" position of Iraqi troops in Anbar province, where the few remaining government-controlled areas have come under repeated attack.
Some of Anbar province fell to ISIS at the start of the year and most of the rest was seized by the Sunni extremists in a lightning sweep through Iraq's Sunni Arab heartland in June.
"I think it's fragile there now," one senior US defence official told AFP.
"They are being resupplied and they're holding their own, but it's tough and challenging."
Dozens of US-led air strikes in western Iraq in recent weeks have helped counter the ISIS fighters and the capital Baghdad remains secure, the official said.
But in stark contrast with northern Iraq, where more capable Kurdish forces have succeeded in recapturing territory from the extremists, the federal army has made little headway, illustrating the urgent need for better training, the official said.
A second defence official said: "It's not a good situation."
The federal army had launched a number of offensives that had fizzled out.
"They start an operation and it stops after a kilometre," the official said.
Anbar province was the main battleground for the Sunni insurgency that erupted after the US-led invasion of 2003 and was eventually defeated with the help of Sunni tribes.
But the Shiite-led government of former prime minister Nuri al-Maliki eventually alienated the Sunni minority, creating fertile ground for ISIS to exploit.