Islamic State group jihadists battling for control of the Syrian town of Kobane suffered some of their heaviest losses yet in 24 hours of clashes and US-led air strikes, monitors said Sunday.

At least 50 jihadists were killed in the embattled border town in suicide bombings, clashes with Kobane's Kurdish defenders and air strikes, the Syrian Observatory for Human Rights said.

Canada, meanwhile, said it was "aware of reports" one of its citizens may have been captured in Kobane, reportedly an Israeli-Canadian woman fighting alongside Kurdish forces.

The Britain-based Observatory also said the US-led coalition battling the IS group hit at least 30 targets in and around Raqa, the jihadists' de facto capital.

There were no immediate details of a toll in the Raqa strikes.

Syrian regime strikes on Sunday killed at least 29 civilians, among them seven women and three children, the group said.

The deaths in Kobane came on Saturday after IS jihadists launched an unprecedented attack against the border crossing separating the Syrian Kurdish town from Turkey.

Kurdish officials and the Observatory alleged the attack was launched from Turkish soil, a claim the Turkish army dismissed as "lies".

IS began advancing on Kobane on September 16, hoping to quickly seize the small frontier town and secure its grip on a large stretch of the Syrian-Turkish border, following advances in Iraq.

- 'Female Zionist soldier' -

At one point it looked set to overrun the town, but Kurdish Syrian fighters, backed by coalition air strikes and an influx of Iraqi Kurdish peshmerga forces, have held IS back.

The US-based monitoring group SITE said IS claimed a woman described as a "female Zionist soldier" had been captured in Kobane.

Some jihadists said she might be Gill Rosenberg, a Canadian-Israeli dual national who had served in the Israeli military and had volunteered to fight with the Kurds, SITE said.

An Israeli foreign ministry spokesman told AFP: "We know nothing about it, but are closely monitoring the information."

A Canadian foreign ministry statement said it was aware of the reports but would not "comment or release any information which may compromise ongoing efforts and risks endangering the safety of Canadian citizens abroad".

In Raqa province, the coalition carried out strikes against at least 30 IS targets on the northern outskirts of the city of the same name and struck Division 17, a Syrian army base which jihadists captured earlier this year.

"We can't say it's the largest set of raids they have carried out, but it's been a long time since we've seen this number of targets hit," Observatory chief Rami Abdel Rahman said.

The coalition began carrying out air strikes against the IS on September 23, and stepped up raids in Kobane in a bid to prevent it falling to the jihadists.

- 'Easy targets' -

The US coordinator of the coalition said earlier this week that at least 600 IS fighters had been killed in air strikes and that the group had made easy targets of its fighters by pouring them into Kobane.

But Syria's Foreign Minister Walid Muallem said the air strikes were having little effect and that unless Turkey closed its border to jihadists, the group would be unharmed by the air strikes.

Damascus has regularly accused Turkey of supporting "terrorism" because of its support for the Syrian opposition.

Turkey denies the allegations.

Erdogan is to receive Russian President Vladimir Putin, whose country is a key ally of Syria, in Ankara on Monday for talks about the conflict, which has killed nearly 200,000 people since March 2011.

At the end of a visit to Turkey, Pope Francis on Sunday urged Muslim leaders worldwide to "clearly" condemn terrorism carried out in the name of Islam.

In Syria, the regime kept up its deadly air strikes, including raids that killed 21 civilians including seven women and two children in Jassem in southern Daraa province on Sunday.

Regime strikes in Andan village in the northern province of Aleppo killed eight civilians including a child, the Observatory said.

Abdel Rahman also said the Al-Qaeda-linked Al-Nusra Front executed 13 opposition fighters in Syria's northwestern province of Idlib.

In neighbouring Iraq, meanwhile, the UN and aid groups warned that the arrival of winter meant more help was needed for 2.1 million people displaced by conflict there.

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