The deaths have been caused by all sides in the conflict. A report by UN Secretary-General Ban Ki-moon blamed "indiscriminate and disproportionate aerial bombings and ground attacks" on areas with large civilian populations by government forces, opposition fighters and "terrorist" groups. Geoffrey Mock, a Middle East specialist at Amnesty International, said both government forces and insurgents have used "weapons that are guaranteed to cause civilian damage".

"What we are seeing in Syria is war crime on both sides," Mock told the New York Times.

The conflict in Syria is now approaching its fifth year with no end in sight. Of the four million people who have fled the country, nearly two million of them are children. Almost three million children are unable to go to school (2.3 million inside Syria, 685,000 refugees).

IBTimesUK looks at the lives – and tragic deaths – of children in Syria.

Syria children
A Syrian man carries the body of a child killed in a reported air strike by government forces in the rebel-held area of Douma, on 7 November 2015 Abd Doumany/AFP
Syria children
A man holds the body of his daughter who was killed by what activists said were air strikes by forces loyal to Syria's President Bashar al-Assad in the Douma neighbourhood of Damascus, on 24 August 2015 Bassam Khabieh/Reuters
Syria children
A Syrian man carries the body of a child following a reported military strike by government forces in the rebel-controlled Bustan al-Qasr district of the northern city of Aleppo on 20 June 2015 Karam al-Masri/AFP

Save the Children is working inside Syria to give children the basics they need to survive. The organisation is providing urgent relief as well as long-term aid to refugee children in neighbouring countries, such as Lebanon and Iraq, and along the route through Europe. You can help.