TURKISH President Tayyip Erdogan has warned the Syrian border town of Kobani is about to fall after Islamic State (IS) fighters pressed home a three-week assault which is said to have cost 400 lives.

The prospect that the town on the Turkish border could be captured by the militants has increased pressure on Turkey to join an international coalition to fight against Islamic State.

US-led airstrikes have so far failed to prevent the IS advance on Kobani, which the militants are targeting as it will enable them to strengthen their grip on the border area and consolidate territorial gains made in Iraq and Syria in recent months.

Mr Erdogan said airstrikes were not enough to defeat IS, and Turkey had made clear additional measures would be needed.

Speaking during a visit to a camp for Syrian refugees, he said: "The problem of Islamic State cannot be solved via air bombardment. Right now, Kobani is about to fall.

"We had warned the West. We wanted three things. A no-fly zone, a secure zone parallel to that and the training of moderate Syrian rebels."

He said Turkey would intervene if there were threats to Turkish soldiers guarding a historic site in Syria that Ankara regards as its territory. But so far Turkey has made no move to get involved in the fighting across the border.

From Turkey, two black IS flags could be seen flying over the eastern side of Kobani. Two airstrikes hit the area and sporadic gunfire could be heard.

The Syrian Observatory for Human Rights monitoring group said it had documented 412 deaths of civilians and fighters during the three-week battle for Kobani.

Plumes of white smoke rose over eastern and central parts of Kobani yesterday as IS fighters used heavy weapons and shells to hit the town.

The radical al Qaeda offshoot has ramped up its offensive in recent days against the mainly Kurdish border town, despite the US-led airstrikes.

An estimated 180,000 people have fled into Turkey from the Kobani region following the IS advance. More than 2,000 Syrian Kurds, including women and children, were evacuated from the town after the latest fighting.

Nato member Turkey, which shares a 500-mile border with Syria and has the most powerful military in the area, has refrained from joining the campaign but the plight of Kobani has increased pressure for the country to act.

However, Turkey has said the scope of the campaign in Syria should be broadened to remove President al Assad from power in Damascus. It has sought a no-fly zone in northern Syria, which would require the coalition to take on Mr Assad's airforce as well as IS, a move the US has not agreed to.

More than 20 Turkish tanks were yesterday parked on a hillside in circular formation around half a mile from the border.

Groups of mainly men travelled towards the border area to witness the clashes and protest against inaction by Turkey to protect Kobani. Turkish police fired tear gas and water cannon at dozens of demonstrating youths in a field near the border.

The US has been bombing IS positions in Iraq since August and extended the campaign to Syria in last month. Arab states have joined both campaigns, while other Western countries, including the UK, are taking part in Iraq but not Syria.

The anti-IS campaign has added a new weapon to its arsenal in Iraq, using US Apache helicopters for the first time.