The Islamic State has claimed responsibility for a series of deadly bomb attacks in Damascus and Homs, which left at least 140 people dead.
David Cameron is making a last push to find support for his EU reforms ahead of a crucial European Council summit on Thursday.
Russia “categorically rejects” allegations of war crimes over the bombing of four hospitals and two schools in Syria on Monday.
As many as 50 people, including 12 children, have been killed in missile attacks on three separate hospitals in northern Syria.
A hospital in the north-western Idlib province of Syria supported by Medecins Sans Frontieres (MSF) has been destroyed in a Russian air strike.