Smoke rises from a village on the outskirts of the Syrian town of Kobani Kai Pfaffenbach/Reuters

Coalition airstrikes against Isis (Islamic State) positions around the Syrian Kurd town of Kobani are said to be the heaviest for days, but the Islamist group continues to attack the town in the hope of securing a valuable strategic position on the Syrian-Turkish border.

Reuters is reporting that Isis bombarded Kobani's town centre with mortars in a bid to break the resistance of Kurdish defenders of the town. Some mortar shells fired by Islamic State are said to have landed inside Turkish soil. The coalition bombarded Islamic State positions, striking at least six targets.

Turkey has so far refused to become involved in saving Kobani, and has refused to allow US planes to use its territory. This means jets have to make flights from USS Carl Vinson in the Persian Gulf several hours away.

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Protesters throw stones at a police vehicle in Ankara AFP

Turkey's large Kurd community are becoming increasingly angry with Ankara's refusal to strike at Islamic State forces.

Turkey's president Erdogan says the country will only get involved if the coalition pledges to also dislodge the regime of President Assad in Syria.

Kurds have staged violent protests across Turkey in which at least 35 have died.

Last week Turkey bombed Kurdish PKK positions in what it said was retaliation for an attack on Turkish troops by rebels.

Meanwhile several hundred Kurds are continuing to hold Kobani and have succeeded in driving out Islamic State from some areas of the town and surrounding hills.

The British-based Syrian Observatory for Human Rights estimates 662 people have died in and around Kobani since fighting started on 16 September, including 20 civilians, 268 Kurdish soldiers and 374 Islamic State fighters.

Kurds fear a massacre will take place if Islamic State succeeds in overrunning the town. Dozens of nearby villages are already under Islamic State control and there have been reports of massacres of civilians by Islamic State's fanatics.