Robbie Williams was humbled by the plight of "vulnerable" child victims of the Haiti earthquakes.

The 'Angels' hitmaker – who is visiting the disaster-stricken country in his position as an ambassador for UNICEF, (United Nations International Children's Fund) - met children affected by January's natural disasters and was visibly moved by the squalid conditions in which they have to live.

He said: "I met children who were injured, who had been separated from their parents and were living in temporary shelters or on the streets. This earthquake hit children the hardest. The children are so vulnerable."

The 36-year-old singer admitted he was outraged by the "risk of violence" which child refugees now face everyday.

He said: "They're living day-to-day without the basic things they need and at risk of violence and abuse. I don't know about you, but I think this is wrong and we need to put it right."

The emotional star is also launching a special challenge for Soccer Aid – a star-studded sports event which takes place on June 6 and raises money for UNICEF - on his return from the trip, called 'Keep It Up For Soccer Aid'.

The 'You Know Me' singer is asking people to be sponsored for the number of 'keepy-uppys' – juggling a football with various parts of the body without letting it fall on the floor – they can do in aid of the organisation.

Speaking of the challenge, Robbie added: "It's really simple, do as many sponsored keepy-uppys as you can to make a real difference to the lives of children."

Other stars who have visited Haiti include Susan Sarandon, Sean Penn, Demi Moore and Gerard Butler.