Tom Hiddleston has spoken of his "heartbreak" over the conflict in South Sudan following a visit to the country as it enters its fourth year of a bitter civil war.
On his second trip to the African nation since February 2015, the British actor met children who had become separated from their families in a displacement camp run by Unicef.
Tom - who is an ambassador for the United Nations agency - said: "Everyone I've met has experienced traumatic events that no one - least of all a child - should ever have to go through.
"It's heartbreaking to see that after three years, innocent children are still bearing the brunt of the conflict.
"The physical reality is that when fighting breaks out, everybody runs in different directions. Children become separated from their families - from their mothers, from their aunts, from their brothers, from whoever is looking after them - and are immediately vulnerable to psychological and physical abuse, hunger, and forced recruitment as child soldiers."
Since war broke out in December 2013, 1.5 million children have been forced to flee their homes, according to Unicef.
Another 17,000 youngsters are said to have been recruited as child soldiers.
During a trip to a camp in Bentiu, in north South Sudan, the 35-year-old met two brothers who had been separated from their mother after the fighting began.
The pair had been living with a neighbour for three years but are due to be reunited with their mother after Unicef tracked her down.
Tom said: "I've seen things in South Sudan that will stay with me forever.
"It's the youngest country in the world, a country which should have so much to look forward to, but the conditions those two boys have to live in - a place still torn apart by civil war - are unimaginable.
"Knowing that they will be reunited with their mother soon is at least a sign of hope in the immense struggle of the people of South Sudan," he added.
Earlier this year Tom said he had used anger fuelled by a previous visit to the country to help him in his role as spy Jonathan Pine in The Night Manager.