09/05/2014 07:57 BST | Updated 09/05/2014 08:59 BST

Oscar Knox, Celtic Fan, Dies Aged 5 From Cancer

Oscar Knox, the five-year-old Celtic fan from Northern Ireland whose battle against cancer captured the hearts of thousands, has died.

The Co Antrim boy was diagnosed with neuroblastoma in 2011 and his brave fight against the disease was shared by his parents, Stephen and Leona, on Twitter and he soon became an online phenomenon.

His parents announced his death to more than 53,000 followers of the Wee_Oscar Twitter account this morning: "Our beautiful, amazing and much-loved son, Oscar James Knox gained his angel wings yesterday afternoon. Sleep tight little man Xx."

An appeal by his family raised hundreds of thousands of pounds over the last three years. The campaign won many high-profile friends and memorably Oscar wreaked havoc during a visit to the offices of Northern Ireland's First Minister Peter Robinson and Deputy First Minister Martin McGuinness at Stormont.

The political leaders led the tributes today. Mr Robinson said his thoughts and prayers were with his parents and sister Isobella.

"Their sense of loss and devastation is immeasurable," he said.

"When I met Oscar I was struck by his infinite energy and sense of fun. He had a tremendous capacity to overcome the challenges he and his family faced together.

"Oscar was an amazing little boy who lived his life to the full and filled those around him with admiration and hope. He will be deeply missed by everyone who met and loved him."

Mr McGuinness said: "Oscar touched the hearts and minds of everyone and inspired countless people through his positive attitude and resilience.

"The day Oscar and his family visited Stormont was one of my most uplifting days in politics and you couldn't help but be enthused by his vibrancy and spirit.

"Oscar was a little warrior who faced down sickness and setbacks and showed all of us how precious life is."

Oscar was an enthusiastic Celtic supporter but his campaign was also backed strongly by Glasgow Rangers fans - a measure of the boy's ability to unite.

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Oscar Knox with First Minister Peter Robinson (right) and deputy First Minister Martin McGuinness

When Celtic played Belfast side Cliftonville in Glasgow last summer in a Champions League qualifier Oscar was the team mascot.

Celtic chief executive Peter Lawwell said: "This is absolutely devastating news and our thoughts and prayers are with Oscar's parents, Stephen and Leona, and his little sister, Izzie, at this desperately sad time.

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"We can't even begin to understand the pain of their loss, but I hope that there will be a small measure of consolation in knowing that there was genuine love and affection for Oscar from the Celtic family throughout the world.

"Oscar's courage throughout his illness was truly inspirational, and it was a real pleasure for everyone at the club to meet Oscar when he was our team mascot last July.

"This is a very sad day for the Celtic family but, more importantly, for the Knox family, and our thoughts and prayers are with them today."