An Australian who joined Kurds battling the Islamic State group in Syria arrived back home Monday with his parents pleading with authorities not to charge him under foreign fighter laws, calling him "a hero".

Ashley Dyball, 23, was detained in Germany while taking a break from a Kurdish military campaign against IS in northern Syria and deported on Saturday night.

Syria's competing opposition factions, including armed groups battling both regime forces and jihadists, will meet in Riyadh next week to find common ground ahead of potential negotiations with Damascus, opposition sources said Friday.

But pressure from Turkey meant the leading Kurdish political and armed groups in Syria were not invited, they said.

Prime Minister David Cameron said Britain should "answer the call" from its allies and take part in air strikes on the Islamic State group in Syria, as he spoke to MPs ahead of a vote on Wednesday.

"We should answer the call from our allies. The action we propose is legal, it is necessary and it is the right thing to do to keep our country safe," he said.

Thousands of people were expected to protest in London Saturday against Britain potentially joining air strikes against the Islamic State (IS) group in Syria.

Parliament is expected to vote on the issue next week after Prime Minister David Cameron pushed MPs to back the move in the wake of this month's Paris attacks.

Outside her home in a town of northeast Syria, four-year-old Baydaa scribbles on a leaflet of religious rules left behind by the Islamic State group as they fled earlier this month.

Her face is adorned with make-up of the sort banned by the jihadist group, which was expelled from Al-Hol by a new U.S.-backed coalition of Kurdish and Arab forces that overran the area on November 12.

Syrian special forces launched an operation "behind enemy lines" to rescue the surviving crew member of a Russian warplane downed by Turkey, Syria's Al-Watan newspaper reported on Thursday.

"Eleven members of an elite unit of the air force intelligence service and a (Russian-language) translator, led by an officer, infiltrated 3.5 kilometers (two miles) behind enemy lines in the Al-Atira region on Tuesday and recovered the airman," the pro-government newspaper said.

Syrian government troops are advancing on "nearly every front" thanks to Russian air strikes that began in September, President Bashar Assad said in an interview released Sunday.

The embattled president also said he favored new peace talks to be hosted in Moscow, but stressed that the Syrian conflict could not be resolved without "defeating terrorism."

Around 1,500 members of Syria's Turkmen minority have fled to the Turkish border to escape renewed fighting in the northwest of the country, a Turkish official said Sunday.

Turkey has expressed concern in recent days over Russian air raids in the area, fearing they are aimed at hitting Syrian opposition fighters and bolstering the regime of President Bashar Assad.

U.S. Republican presidential hopeful Ben Carson on Thursday compared refugees fleeing Syria's civil war and Islamic State extremists to rabid dogs.

Carson, a retired neurosurgeon and a top contender in his party's 2016 race for the White House, made the remarks at a campaign stop in the southern U.S. state of Alabama.

Syria's army and rebels pursued talks to reach a 15-day ceasefire in a rebel stronghold east of Damascus Thursday as fighting subsided in the area, a monitor and security sources said.

The two sides had been locked in talks overnight in the hopes of reaching a ceasefire deal by 6:00 am (0400 GMT), in what would be the first such agreement since new international efforts on ending Syria's conflict began in Vienna last month.