British actor Michael Sheen has warned of a "cold weather catastrophe" after visiting some of Syria's refugees in their tent city in Lebanon.
He spent time with families living in improvised shacks, often without access to heating and basic services, at the Faida camp in Lebanon's Bekaa valley.
The actor, who starred in The Queen and Frost/Nixon, also joined in with a lesson among school children who are struggling with the trauma of war:
Travelling as a guest of the aid agency UNICEF, Sheen said he witnessed the difference that basic supplies like blankets and hats can mean to a refugee family:
Syrian children have lost everything - loved ones, their homes, their education - and now winter is a new and potentially deadly threat. Seeing the faces of children who had nothing receive a full supply of winter clothes - from hats to coats to thermal underwear - was emotional and showed what can be done to change lives.
More than one million children have now fled war-torn Syria and are struggling to cope as refugees in neighbouring countries, according to UN figures.
Lebanon is hosting the largest number of Syrian refugees - more than 800,000 have arrived in the country, half of whom are children.
The tiny nation's resources are being stretched to breaking point under the strain of coping with the influx, UNICEF said.
"As we begin to feel winter weather bite in the UK, I urge everyone who thinks there is nothing they can do about Syria to think again," Sheen said.
"We can take action now to donate to children facing extreme conditions and help stop millions of innocent Syrian children losing their childhoods."
All money raised for UNICEF's work for the children of Syria will be matched pound for pound by the UK Government until the end of January.
Donate £5 to the children of Syria by texting 'SYRIA' to 70007 or phoning 0800 044 5885
Donate online by visiting http://www.unicef.org.uk/