Bono thinks B.B. King was a ''guitar genius''.

The 55-year-old U2 star has paid a glowing tribute to the late blues singer-songwriter, who passed away earlier this month, and also revealed B.B. and his band-mate The Edge used to love playing poker together while on tour.

He told The Sun newspaper: ''B.B. had a volcano of a voice as well as being a guitar genius. He was one hell of a singer.

''He came on the road with us for a while on the Lovetown tour in 1988-89 and he was a great gambler.

''The Edge used to play poker a lot with B.B., they would even bet on which elevator would arrive first. In my eyes B.B. was one of the three Memphis kings alongside Elvis and Martin Luther King.''

Meanwhile, The Edge praised the late singer for the ''inspiring'' way he dealt with discrimination.

He said: ''The hardships he had to endure growing up on a cotton farm.

''He had some really difficult times with discrimination and came through it all with the most unbelievable grace which was so inspiring.''

B.B. died on May 14, aged 89, with authorities in the US currently investigating claims he was poisoned.