Stevie Wonder told thousands of fans watching him perform in London on Saturday night he is due to have a kidney transplant in September.

The singer, songwriter and musician told the crowd at an event in Hyde Park that he had a donor lined up, and was making the announcement to avoid rumours spreading about his health.

"I'm going to have surgery, I am going to have a kidney transplant in September of this year," he said as he finished his performance, according to footage posted on Twitter by those at the concert.

The sixty-nine year old, who has won more Grammy awards than any other artist and whose hits include "Superstitious", "I Just Called to Say I Love You" and "Isn't She Lovely", did not reveal what was behind him needing the transplant.

"I'm all good, I'm all good, I'm all good. I have a donor it's all good," he added after a supportive cheer from the crowd.

"I want you to know I came here to give you my love and to thank you for your love, you ain't got to hear no rumours about nothing, I told you what's up, I'm good."