Kurdish fighters backed by US-led air strikes were locked in fierce fighting Wednesday to prevent a key Syrian border town from falling to Islamic State group jihadists.
It came as 41 children were reported dead in twin bombings at a school in the government-controlled central city of Homs, which has been devastated by the three-year civil war.
Anti-jihadist air strikes and heavy clashes in the besieged town of Ain al-Arab on the Turkish border killed at least 18 people -- nine militants and nine Kurdish fighters, monitors said.
Ambulances ferried wounded fighters for treatment in Turkey amid mortar fire, with some rounds hitting very close to the border, an AFP correspondent on the Turkish side reported.
The twin blasts in Homs farther south hit a neighbourhood inhabited mainly by the Alawite community of Syrian President Bashar al-Assad, which has been frequently targeted by rebels and jihadists.
One attacker carried out both bombings, planting a device at one location before blowing himself up at another, said the Syrian Observatory for Human Rights.
The dead children were among at least 48 people killed.
There was no immediate claim of responsibility.
About 191,000 people have been killed since an uprising against Assad erupted in 2011, escalating into a several-sided war involving pro-government forces, hardline jihadists and more moderate rebels.
Near the Turkish border, Kurdish forces have been on the defensive for more than two weeks in the face of a jihadist assault that sent tens of thousands of refugees streaming across the frontier.
With IS fighters less than three kilometres (two miles) from the town, the US-led coalition carried out three air strikes in the area Tuesday and Wednesday, the Pentagon said.
They destroyed an IS armed vehicle, an artillery piece and a tank, US Central Command said, bringing to seven the number of raids since Saturday around the town, known by the Kurds as Kobane.
- 'Thrown into the air' -
At least eight jihadist fighters were killed when a tank was hit, according to the Observatory, a Britain-based monitoring group.
"Kurdish fighters on the front lines saw the bodies literally being thrown into the air" by the blast, Observatory director Rami Abdel Rahman said.
One refugee told AFP that the light weapons available to the town's defenders meant that they could only engage the jihadists at close quarters.
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Ain al-Arab would be a major prize for IS, giving it unbroken control of a long stretch of the Syrian-Turkish border.
The US-led coalition of Western and Arab allies has been flying missions in Syria since last week against IS, an extremist Sunni group that has seized control of large parts of the country and neighbouring Iraq.
Backed by coalition raids, Kurdish forces Tuesday attacked the town of Rabia on the Syrian border, north of jihadist-controlled second city Mosul, and south of oil hub Kirkuk, commanders said.
An officer said up to 12 jihadists were holed up in a clinic and surrounded.
Farther south, Sunni Arab tribesmen repelled a renewed jihadist attack in the town of Dhuluiyah in fighting that killed 14 people, police and medics said.
And a coalition warplane killed nine militants in a strike on an IS base near Hawijah, a senior Iraqi intelligence officer said.
In Baghdad, a suicide car bombing ripped through a busy commercial street, killing at least 14 people, police and medical sources said.
Iraqi Foreign Minister Ibrahim al-Jaafari said any international assistance in the fight against IS should preserve "Iraqi sovereignty," and also thanked Iran for its support.
"Iran has provided assistance to Iraq, as have some other countries. This is not a secret and we have to thank them for it," he said.
The Pentagon has warned there would be no quick and easy end to the fighting, with spokesman Rear Admiral John Kirby saying: "No one should be lulled into a false sense of security by accurate air strikes."
- Turkey warning -
And Turkish President Recep Tayyip Erdogan said dropping "tons of bombs" on IS would provide only temporary respite.
NATO member Turkey, after months of caution, has decided to harden its policy, with parliament due to debate Thursday a government request to authorise military action against IS in both Iraq and Syria.
Australia announced that its jets were joining the air campaign in Iraq in a support capacity.
Prime Minister Tony Abbott, who has called IS an "apocalyptic death cult," said the aircraft would provide reconnaissance and refuelling support.
Britain said its jets targeted two IS vehicles west of Baghdad overnight in their second strikes on the jihadists in Iraq in as many days.
France, which currently has six Rafale warplanes and just under 1,000 soldiers based in the United Arab Emirates, said it would deploy three more Rafales and a warship in the coalition fight against IS in Iraq.