An Islamic State fighter gestures from a vehicle in the countryside of the Syrian Kurdish town of Kobani, after the militants took control of the area on Tuesday. But US-led air strikes on Wednesday pushed the fighters back to the town's edges.

Reuters/Mursitpinar, Turkey/Ankara

US-led air strikes on Wednesday pushed Islamic State fighters back to the edges of the Syrian Kurdish border town of Kobani, which they had appeared set to seize after a three-week assault, local officials said.

The town has become the focus of international attention since the Islamists' advance drove 180,000 of the area's mostly Kurdish inhabitants to flee into adjoining Turkey, which has infuriated its own restive Kurdish minority - and its NATO partners in Washington - by refusing to intervene.

Islamic State hoisted its black flag on the eastern edge of the town on Monday but, since then, air strikes have been redoubled by a US-led coalition that includes Gulf states seeking to reverse the jihadists' dramatic advance across northern Syria and Iraq.

Intense gunfire could be heard on Wednesday morning from across the Turkish border.

"They are now outside the entrances of the city of Kobani. The shelling and bombardment was very effective and as a result of it, IS have been pushed from many positions," Idris Nassan, deputy foreign minister of Kobani district, told Reuters by phone.

"This is their biggest retreat since their entry into the city and we can consider this as the beginning of the countdown of their retreat from the area."

Islamic State had been advancing on the strategically important town from three sides and pounding it with artillery despite dogged resistance from heavily outgunned Kurdish forces.

Defence experts said it was unlikely that the advance could be halted by air power alone - a fact that left not only Washington but also the Syrian Kurds' ethnic kin across the border demanding to know why the Turkish tanks lined up within sight of Kobani had not rolled across the frontier.

However, many Turks outside the southeast think it is far better to risk alienating the Kurds than be sucked into a ground war in Syria.

At least 12 people died and dozens more were injured on Tuesday as sympathisers of the outlawed Kurdish PKK militant group clashed with police and Islamists in towns and cities across Turkey's predominantly Kurdish southeast as well as in Istanbul and Ankara.

Authorities imposed curfews in five southeastern provinces and sent troops and tanks onto the streets of Diyarbakir, the largest Kurdish city in the region, to try to quell the unrest.

An unnamed senior US official told the New York Times on Tuesday that there was "growing angst about Turkey dragging its feet to act to prevent a massacre less than a mile from its border".

Beyond becoming a target for Islamic State, which is active along much of Syria's border with Turkey, it fears being sucked into Syria's complex civil war and perhaps even having to fight the forces of its declared enemy, President Bashar al-Assad.

With this in mind, President Tayyip Erdogan has set stringent conditions for Turkey to contemplate attacking Islamic State on Syrian sovereign territory.