People stuck in war-ravaged Aleppo do not have the luxury of refusing help from jihadists, a high-level member of Syria's main opposition said, lashing out at international "inaction" in breaking the siege.

Nearly half of Russians fear that Moscow's bombing campaign in Syria could spark World War III, a poll showed Monday.

The Kremlin said Friday that President Vladimir Putin did not think it was time to resume air strikes on Aleppo after the defense ministry requested that a moratorium on bombing be lifted.

Russia on Thursday dismissed as "unconvincing" the findings of a UN-led investigation showing that Syrian forces had carried out three chemical attacks, and said no sanctions should be imposed.

"We believe that the proof is not there for any punitive action to be taken. It's simply not there," Russian Ambassador Vitaly Churkin told reporters following a closed-door Security Council meeting. 

The European Union on Thursday added 10 top Syrian officials to its sanctions blacklist for their role in the "violent repression" of the civilian population.

Air strikes that hit a school in rebel-held Idlib province in northwest Syria killed 22 children and six teachers, the U.N. children's agency UNICEF said Wednesday.

Sixteen civilians, including three children, were killed on Monday in heavy bombardment across rebel-held Idlib province in northwest Syria, a monitoring group said. 

Nearly 100 civilians have been killed in a two-month offensive by Turkey and allied rebels in northern Syria, a monitoring group said on Monday. 

Clashes and air strikes shook the Syrian city of Aleppo on Sunday, leaving three civilians dead as heavy fighting resumed after the end of a three-day ceasefire declared by government ally Russia.

Around 620 rebels and their families began evacuating a besieged town southwest of the Syrian capital on Wednesday under a deal with the government, a local official told AFP.