Turkey's president said on Tuesday the Syrian Kurdish town of Kobani was "about to fall" as Islamic State fighters pressed home a three-week assault that has cost a reported 400 lives and forced thousands to flee their homes.

The prospect that the town could be captured by Islamic State, who are now within city limits, has increased pressure on Turkey to join an international coalition to fight against the jihadists.

Islamic State wants to take Kobani in order to strengthen its grip on the border area and consolidate the territorial gains it has made in Iraq and Syria in recent months. US-led air strikes have so far failed to prevent its advance on Kobani.

Turkey said it was pressing Washington for more air strikes, although President Tayyip Erdogan said bombing was not enough to defeat Islamic State, and he set out Turkey's demands for additional measures before it could intervene.

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

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

He said Turkey would take action 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.

US Secretary of State John Kerry and Turkish Prime Minister Ahmet Davutoglu had spoken twice in recent days to discuss the situation, State Department spokeswoman Jen Psaki said.

"Turkey is determining what larger role they will play," Psaki told a daily briefing. "They have indicated their openness to doing that, so there is an active conversation about that."

Retired US General John Allen, the envoy charged with building the coalition against Islamic State, and his deputy Brett McGurk will visit Turkey later this week for talks.

U.N. Syria envoy Staffan de Mistura said Turkey had been generous in receiving refugees from Kobani but the international community needed to protect the town. "What is needed now is concrete action," he said, without elaborating.

France said it was vital to stop Islamic State's advance on Kobani, and was discussing with Turkey what could be done. "A tragedy is unfolding, and we must all react," Foreign Minister Laurent Fabius told parliament.

But some analysts doubt the will exists among Western allies to take further action.

"It's the coalition of the unwilling, each country is doing the bare minimum, particularly in Syria," said Fadi Hakura at the London-based think tank Chatham House.

From across the Turkish border, two Islamic State flags could be seen flying over the eastern side of Kobani.

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.

The US military said it and allied air forces launched strikes on Islamic State in Syria on Monday and Tuesday. In the Kobani area the raids destroyed armed vehicles, a tank and a vehicle carrying anti-aircraft artillery.

On the ground, a burning tank, apparently belonging to Islamic State, could be seen on the western edge of town. There were also clashes on the northern fringe and mortar explosions could be heard to the northeast.

Islamic State fighters were using heavy weapons and shells to hit Kobani, senior Kurdish official Asya Abdullah told Reuters from inside the town, estimated by the U.N. on Tuesday to contain possibly a few hundred remaining residents.

AIR STRIKES

Islamic State, an al Qaeda offshoot, has ramped up its offensive in recent days against the mainly Kurdish border town, despite being targeted by US-led coalition air strikes aimed at halting its progress.

"There were clashes overnight. Not heavy, but ISIS is going forward from the southwest. They have crossed into Kobani and control some buildings in the city there," said Rami Abdulrahman, head of the Observatory, a group that monitors the conflict with a network on the ground. ISIS is a former name for Islamic State.

"They are about 50 metres (55 yards) inside the southwest of the city," Abdulrahman said.

An estimated 180,000 people have fled into Turkey from the Kobani region following the Islamic State advance. More than 2,000 Syrian Kurds including women and children were evacuated from the town after the latest fighting, a member of the Kurdish Democratic Union Party (PYD) said on Monday.

Before the offensive, Kobani, known as Ayn al-Arab in Arabic, was home to refugees from the civil war that pits rebels against President Bashar al-Assad and has deteriorated into hundreds of localised battles between different factions.

The most powerful of the myriad militias fighting against Assad, Islamic State has boosted its forces with foreign fighters and defectors from other rebel groups. It gained additional heavy weaponry after its fighters swept through northern Iraq in June, seizing arms from the fleeing Iraqi army.

The group released a video showing dozens of men said to be from Ahrar al-Sham, a rival Islamist group that has clashed with it in the past, pledging allegiance to its leader Abu Bakr al-Baghdadi, the SITE monitoring service said on Monday.

Westerners have also fought for the Kurds against Islamic State. A man describing himself as a US citizen and former soldier from Ohio said in a video interview with Reuters in Syria that he had come to join Kurdish fighters.

Identifying himself as Brian Wilson, he said other Americans had come to Syria to fight Islamic State.

The FBI asked Americans on Tuesday to help identify a masked man who speaks in what is believed to be a North American accent in a video that Islamic State militants released last month. It also requested the public's assistance "in identifying US persons going to fight overseas with terrorist groups or who are returning home from fighting overseas."

The United States has been bombing Islamic State positions in Iraq since August and extended the campaign to Syria in September. Arab states have joined both campaigns, while other Western countries are participating in Iraq but not Syria.

Canadian lawmakers on Tuesday approved government plans to send fighter jets to Iraq, where they will take part in US-led air strikes against Islamic State militants for up to six months.

Two months into the US campaign, the US military has added a new weapon to its arsenal in Iraq, using Apache helicopters for the first time, US officials said on Monday.

Turkish Deputy Prime Minister Yalcin Akdogan called for more US action. "Our government and our related institutions have emphasised to US officials the necessity of immediately ramping up air bombardment in a more active and efficient way," he said, according to the website of the television channel AHaber.

Turkey, a NATO member that shares a 900-kilometre (500-mile) border with Syria and has the most powerful military in the region, has so far refrained from joining the campaign, but the plight of Kobani has increased pressure to act.

Turkey says the scope of the campaign in Syria should be broadened to seek to remove Assad from power. It has sought a no-fly zone in northern Syria, which would require the coalition to take on Assad's air force as well as Islamic State, a move Washington has not agreed to.

PROTESTS IN TURKEY

At least nine people were killed and dozens wounded in demonstrations across Turkey on Tuesday as Kurds demanded the government do more to protect Kobani, local media reported.

Police fired tear gas and water cannon to disperse protesters who burnt cars and tyres as they took to the streets mainly in Turkey's predominantly Kurdish eastern and southeastern provinces. Clashes also erupted in the biggest city Istanbul and in the capital Ankara.

The victims included five people killed in Diyarbakir, the largest Kurdish city in the southeast, which saw clashes between protesters and police.

In Geneva, angry Kurds held a protest at the United Nations, while in Brussels they invaded the European Parliament. They waved flags bearing the portrait of jailed Kurdish Workers Party leader Abdullah Ocalan.

The brother of British aid worker Alan Henning, who was beheaded by Islamic State, said Britain should put troops on the ground in the Middle East to fight against the militants.

Kidnappings are common in Syria's civil war, often used for ransom. Catholic news agency Fides quoted Bishop Georges Abou Khazen, the Apostolic Vicar of Aleppo, as saying a parish priest and about 20 Christians have been kidnapped from a Syrian village near the border with Turkey. – Reuters