Lisbon:Portuguese football star Cristiano Ronaldo, a Save the Children ambassador, said Syrian children affected by the war were "real heroes" and called for them not to lose hope.

"Hello, this is for children of Syria. We know that you have been suffering a lot. I am a very famous player, but you are the true heroes, don't lose your hope," he said in a video message posted on social media network Twitter on Friday, reports Xinhua.

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"The world is with you, we care about you. I am with you," he added.

Save the Children said his "generous donation" would help families buy clothes, food and medical care.

Syria has been undergoing a four-year battle over its largest city, Aleppo, with UNICEF stating earlier this month that around 100 unaccompanied children were trapped in a building in the east of the city.

Tens of thousands of people have been killed and hundreds of thousands displaced since 2012.