Bono wrote a song for Frank Sinatra shortly before he passed away.

The 62-year-old star - who is best known as the lead singer of U2 - has revealed that he wrote a song for the music icon, but "he passed away before he could record it".

Bono shared: "He was a tough guy and I am attracted to tough guys.

"He told me, ‘You are the only man with an earring I am going to like’.

"We wrote a song for him called 'Two Shots Of Happy, One Shot Of Sad' but sadly he passed away before he could record it."

Sinatra died in May 1998, aged 82, after suffering a heart attack.

Bono, meanwhile, has written a new memoir called 'Surrender', and he's explained the motivation behind the project.

The chart-topping star - who is also well-known for his activism and his philanthropic work - said on 'The Graham Norton Show': "I wanted to explain to my friends and family what I had done with their lives.

"They gave me permission to be an artist and an activist travelling around the world, and we don’t really talk about that stuff at the dinner table.

"It turns out that the most extraordinary thing about me are the relationships I am in.

"I met most of them in one week at school and I think the longevity comes from the community of people that knows who you are and how you became who you are, we have shared memories."

Bono also revealed that he's planning to record some new music.

Asked whether fans can expect new music soon, he shared: "We want to make a really unreasonable guitar record, real, proper rock and roll."