Britain and France criticised Russia's role in Syria's war on Tuesday and said Moscow must stop the conflict rather than fuelling it, after missile strikes killed dozens of civilians on Monday.

Almost 50 civilians were killed when missiles hit at least five medical facilities and two schools in rebel-held areas of Syria on Monday, according to the UN, which called the attacks a blatant violation of international law.

Turkish Prime Minister Ahmet Davutoglu blamed Russia for at least one of the missile strikes, when civilians and children were killed in a school and hospital in the town of Azaz, calling it an "obvious war crime".

"The reported air strikes conducted on hospitals in northern Syria in recent days could amount to war crimes and must be investigated," British Foreign Secretary Philip Hammond said in a statement.

"I am appalled that the Assad regime and its Russian supporters are still bombing innocent civilians despite the agreement last Thursday to a cessation of hostilities ... Russia needs to explain itself, and show through its actions that it is committed to ending the conflict, rather than fuelling it."

Russia, which has said it is targeting terrorist organisations and their allies, does not have a vessel in its Caspian Sea flotilla that is capable of hitting a hospital in Syria's Idlib governorate, a Defence Ministry spokesman was quoted as saying by Russian news agencies.

France's new Foreign Minister Jean-Marc Ayrault, who on Monday accused Syria's government and its backers of carrying out war crimes, told lawmakers that the immediate urgency was to protect civilians.

"All bombings must stop. It's unacceptable that hospitals and schools are targeted. These acts are flagrant violations of international law," he said.

Last week in Munich, international powers agreed to try to bring about a "cessation of hostilities" within a week, and US Secretary of State John Kerry accused Russia of hitting legitimate opposition groups with its bombing campaign.

Russian Prime Minister Dmitry Medvedev said the accusations were "just not true".

Ayrault said the Munich deal must be respected.

"Of course, we talk to Russia, but we have demands and our demands today are for the respect of the commitments made in Munich. Russia, like other partners, agreed to end hostilities, end bombings and allow humanitarian aid.

"It's not sentamentalism to say that there are millions of people that are under bombs who have no solution but to flee and become refugees."-Reuters