Turkey's parliament Thursday authorised military action against the Islamic State jihadist group, whose fighters have battled their way to the doorstep of a key town across the border in Syria.

The move allows the deployment of armed forces in Syria and Iraq, as well as the transit of foreign forces in Turkish territory for operations against IS militants.

The broad mandate does not commit Turkey to sending soldiers into the two neighbouring countries, where IS has captured large areas, declaring an Islamic "caliphate" and committing widespread atrocities.

Washington, which has been striving to build an international alliance against the jihadists, welcomed Turkish lawmakers' decision.

State Department spokeswoman Jen Psaki said there have been numerous high-level discussions with Turkish officials on fighting the IS threat, and that Washington looks "forward to strengthening that cooperation".

But Iran warned Ankara against further stoking tensions in the region, with Foreign Minister Mohammad Javad Zarif telling his Turkish counterpart that "countries in the region must act with responsibility and avoid aggravating" matters.

Five Arab nations have participated in the US-led strikes on Syrian soil while the same number of European countries have committed aircraft to Iraq.

Following talks with France's defence minister, US Defence Secretary Chuck Hagel said the two discussed the possibility of Paris extending its participation in the American-led air war to include action on Syrian territory.

But Jean-Yves Le Drian would not confirm or deny that the subject came up during his talks at the Pentagon.

He would only say that France had joined the air strikes in Iraq because Baghdad had made a formal request under the UN charter.

- Fresh raids -

Fresh US-led raids in Syria on Thursday destroyed an IS checkpoint near the besieged Syrian border town of Kobane and hit two tanks elsewhere, the Pentagon said.

In Iraq, coalition air strikes hit a number of IS vehicles as well as a building used by the jihadists.

Britain said it would send two more fighter jets on Friday to join in the battle, but despite the air support, the fightback is proving slow.

At least 17 members of the Iraqi security forces were killed along with 40 jihadists in overnight attacks on two security force bases in the west of the country.

Kurdish militiamen, meanwhile, were locked in fierce fighting to prevent Kobane -- also known as Ain al-Arab -- from falling to IS.

Heavy mortar fire around the town was heard across the border, an AFP correspondent reported.

"There are real fears that the IS may be able to advance into the town of Kobane itself very soon," the Syrian Observatory for Human Rights monitoring group warned.

The town would be a major prize for IS, giving it unbroken control of a long stretch of the border.

- Kurds outgunned -

A Kurdish official inside Kobane acknowledged that the better armed IS fighters had advanced during the night.

"They are closer, two to three kilometres (less than two miles) in some places," Idris Nahsen told AFP by telephone.

"Compared to IS, our weaponry is simple. They have cannons, long-range rockets and tanks."

The UN human rights chief described the array of violations and abuses perpetrated by IS and associated groups as "staggering".

"Many of their acts may amount to war crimes or crimes against humanity," Zeid Ra'ad Al Hussein said.

His office accused the jihadists of crimes "on a massive scale," including beheadings, abductions, torture and forcing women and young girls into sexual slavery.

As the jihadists neared the outskirts of Kobane, there was a quickening of the exodus of civilians which had already seen tens of thousands take refuge across the border in Turkey.

"Kobane is practically empty of its residents now," Observatory director Rami Abdel Rahman told AFP.

- US eyes air base -

The United States is pressing Ankara for the use of the Incirlik air base in southern Turkey by US jets launching assaults on IS in Syria.

But it is unclear if Turkey will allow the transit of lethal weaponry and may restrict the authorisation to humanitarian aid and non-lethal supplies.

Turkish President Recep Tayyip Erdogan pressed the West on Wednesday to find a long-term solution to the crises in Syria and Iraq, saying dropping "tonnes of bombs" on IS would provide only temporary respite.

US officials kept up their warnings that such a solution would take time.

Retired US general John Allen, who is leading the international effort against IS, told CNN "it could take years" to train a Syrian rebel force to take on the jihadists.

Allen arrived in Iraq Thursday to meet government officials and regional leaders on the fight against IS, the US State Department said.

Washington is counting on defeating IS fighters first in Iraq through a combination of Kurdish forces, Iraqi army troops, Shiite volunteers and a militia or "national guard" of Sunni Arab tribes -- which does not yet exist.

In Syria, the US is pinning its hopes on training and arming a new rebel army composed of vetted "moderate" recruits, at a rate of about 5,000 fighters a year.

US, France discuss potential French role in Syria: Hagel
Washington (AFP) Oct 03, 2014 - US and French defense chiefs on Thursday discussed the possibility of France taking part in the American-led air war against Islamic State jihadists in Syria, Defense Secretary Chuck Hagel said.

But his French counterpart, Jean-Yves Le Drian, would not confirm or deny that the subject came up during his talks at the Pentagon.

"Yes, we did discuss possibilities of France's involvement in Syria," Hagel said at a joint news conference.

The talks in Washington came as IS militants in Syria closed in on a key town near the Turkish border, Kobane, despite US air strikes in support of besieged Kurdish fighters.

France is one of five European countries that have committed aircraft to the campaign in Iraq but none of them are involved in the US-led air attacks on IS in neighboring Syria. Five Arab countries are participating in the American-led bombing raids there.

France has provided weapons to Syrian rebels fighting both the Damascus regime and the IS group.

Le Drian said France was participating in air strikes against IS in Iraq because Baghdad had made a formal request under the UN charter.

"France is there because of that request. And we are in the coalition because of that request," he said.

Pressed again on the Syria issue by French journalists after the news conference, Le Drian said: "I cannot answer a question that was not asked."

The minister has previously suggested that Paris had not ruled out an eventual role in the Syria campaign.

- A 'difficult and long' effort -

On Wednesday, the French military said it would deploy three more fighter jets and a naval ship to the Middle East to bolster support for Iraqi forces fighting the IS militants.

Echoing warnings from President Barack Obama and top commanders, Hagel said the fight against the Sunni jihadists would deliver no easy victories.

"This effort against ISIL (IS group) with our coalition partners, both in Syria and Iraq, is going to be difficult and it's going to be long.

"And there were no misconceptions when we started this that there would be any quick finish," Hagel said.

Asked about the timeline for training Iraqi forces, Hagel said he didn't know how long it will take.

Le Drian said both countries had "excellent cooperation" between their spy agencies but sidestepped a question as to whether US missile strikes on Al-Qaeda militants near Aleppo on September 23 were based on French intelligence.

Both Hagel and Le Drian welcomed a vote by Turkey's parliament approving military action against the IS group.

Turkey has often proposed creating a "buffer zone" along its border with Syria to protect civilians and stem the flow of refugees.

Hagel, however, said the US government was not currently considering carving out a buffer zone in northern Syria, but remained open to discussing various "options" with the Turkish government.

"We continue to talk with Turkish government about many options but there are no plans for that option right now," Hagel said.

The US military's top officer, General Martin Dempsey, has said a safe zone would require round-the-clock air patrols and a substantial ground force to enforce it.

In his opening remarks, Le Drian focused mainly on the threat posed by Islamist extremists across the Sahel region in Africa.

The minister thanked Hagel for America's assistance to French forces in Mali and elsewhere in Africa, where the US military has provided surveillance drones, transport and refueling aircraft.

Washington planned to continue to aid France in its efforts against violent extremism in the Sahel, Hagel said.