Turkey on Friday expressed alarm over the viability of an upcoming ceasefire agreed between Syria's warring parties, as the Syrian regime and its ally Russia pressed ahead with an offensive.

"We support the ceasefire in principle. Turkey has played an active role in the making of this decision," presidential spokesman Ibrahim Kalin told reporters in Ankara.

Intense Russian air strikes battered rebel bastions across Syria on Friday, a monitor said, just hours before a midnight deadline for a landmark ceasefire in the country's five-year civil war.

With the ceasefire due to take effect at 2200 GMT, U.S. President Barack Obama has warned Damascus and key ally Moscow that the "world will be watching".

The UN Security Council is expected to vote Friday on a U.S.-Russian draft resolution endorsing the Syria ceasefire, diplomats said.

The 15-member council is set to meet as of 2000 GMT to hear a report from UN envoy Staffan de Mistura and could vote on the measure at that session.

Libya's internationally recognized government on Thursday denied reports that French special forces had been fighting the Islamic State group in the troubled country, after the rival administration in Tripoli confirmed them.

The recognized government "didn't allow and won't allow any foreign forces to enter Libyan territories", spokesman Hatem el-Ouraybi told official news agency LANA.

An Israeli security guard was "very seriously" wounded overnight in a suspected Palestinian attack in a West Bank settlement, police said on Friday.

Police called to a shopping centre in the Maaleh Adumim settlement found "a 47-year-old man, a guard at the mall, lying on the ground with multiple stab wounds on his body," a police statement said.

At least nine people were killed on Thursday in a double suicide bombing targeting a mosque frequented by Shiite worshipers in the northwest of the Iraqi capital, police said.

The U.N.'s Syria envoy said the war-battered country is facing a "crucial day" ahead of a deadline of midnight Friday for a partial truce brokered by Moscow and Washington.

President Bashar Assad's regime and Syria's top opposition grouping have said they will abide by the ceasefire plan, but it has been plagued by doubts after the failure of previous peace efforts.

Russia was set to deport three Syrian refugees on Thursday back to Damascus from a Moscow airport, rights activists said, in a move condemned as "shameful" by Amnesty International.

"One has just called... they are being held under guard, under police escort," head of the migrant rights group The Civic Assistance Committee, told AFP around 1500 GMT.

Israeli President Reuven Rivlin said Thursday he was delaying a scheduled visit to Australia next month to instead hold talks in Russia that are likely to focus on Syria.

"Due to regional developments which have occurred in the Middle East, and the need for a meeting between the two presidents in Moscow, President Rivlin has been forced to postpone his planned visit to Australia", Rivlin's office said.

Iran has withdrawn a "significant number" of its Revolutionary Guards troops from the Syrian battlefield, U.S. Secretary of State John Kerry said Thursday.

Iran is an ally of Syria's President Bashar Assad and has sent members of the elite force to act as "advisers" to his forces and to organize militia units with volunteers from Iran, Iraq and Afghanistan.