Paul McCartney says he is devastated to hear of George Harrison's death.
He paid tribute to the guitarist's courage through his long battle with cancer.
McCartney says he had always viewed Harrison, who he introduced to John Lennon, as a sibling.
Speaking outside his London home, he said: "I am devastated and very, very sad. We knew he'd been ill for a long time.
"He was a lovely guy and a very brave man and had a wonderful sense of humour. He is really just my baby brother."
McCartney said that although he knew George had been ill for quite some time he said he has always hoped that some kind of miracle might happen.
He said: "He had a long battle with his cancer and I saw him a few weeks ago and he was full of fun and he always was.
"A lovely guy who is full of humour as I was saying. When I saw him last time he was obviously very unwell but he was cracking jokes like he always was and he'll be sorely missed. He's a beautiful man. The world will miss him."
Yoko Ono says Harrison brought magic to the lives of those who knew him. She says Harrison's family, who was at his bedside as he died in Los Angeles, was the closest and most loving imaginable.
"George has given so much to us in his lifetime and continues to do so even after his passing, with his music, his wit and his wisdom."