Pope Francis has called child refugees "defenceless" in a message he will use to urge world leaders to accept more displaced youngsters.

In a speech to mark World Day of Migrants and Refugees, the Catholic leader described migration as a phenomena which affects "all continents" and is "growing into a tragic situation of global proportion".

On Sunday aid officials said they feared more than 100 people had drowned off the coast of Libya, after a boat carrying migrants capsized.

It's thought 110 people were on board and only 4 survivors had been found so far.

Hasan Ullah, 34, from Pakistan, stands near a fence, at the snow-covered refugee camp of Vagiohori village, about 45 kilometers east of Thessaloniki

Highlighting the plight of child refugees, the Pontiff said: "I feel compelled to draw attention to the reality of child migrants, especially the ones who are alone.

"In doing so I ask everyone to take care of the young, who in a threefold way are defenceless: they are children, they are foreigners, and they have no means to protect themselves.

"I ask everyone to help those who, for various reasons, are forced to live far from their homeland and are separated from their families."

The pontiff's been supported by the Christian charity World Vision UK, which has repeatedly called upon the UK government and local councils to do all they can to help child refugees.

A migrant sits on a chair outside a tent at the snow-covered refugee camp of Vagiohori

Explaining why it's important children are protected from conflict, senior humanitarian policy advisor Johan Eldebo told Premier: "Children who grow up listening to bombs falling next to their homes, listening to gunfire, witnessing their friends or even family members die due to conflict or tragedy, that is a memory that they will take with them for the rest of their lives."

More than half of the 65 million people forced to flee their homes due to conflicts, persecution and other disasters around the world, are children.

Eldebo also told Premier about young refugees he met in Serbia last winter who had fled Syria.

He explained: "There were children living outside in the cold... They had walked from Syria for about a month and not the entire family had survived; some of the siblings (younger children) had died on the way over.

"They didn't have winter coats, they didn't have enough food at that point. What they were trying to do was to get to places like Germany, like the UK and like Sweden, to be able to live in safety and to be able to be warm when it's cold outside."

The UN's Refugee Agency estimates that nearly nine in ten of the world's refugees are sheltered by developing countries, rather than developed countries like the UK.

Listen to Premier's Alex Williams speaking to Johan Eldebo: