One Direction's success is "absolutely nuts" says Michael Bublé.

The Canadian crooner is impressed by what the British five-piece have achieved in such a short space of time.

Bublé loves the fact that One Direction - comprising Harry Styles, Niall Horan, Zayn Malik, Liam Payne and Louis Tomlinson - have remained down-to-earth despite their international achievements.

He explained: "They're really nice kids and it seems that even with all this craziness that's surrounded them they've somehow managed to stay really normal and fun. It's all absolutely nuts, but I think they have good parents.

He added in the interview with British magazine Closer: "When I talk to Niall Horan he'll still say: 'I can't believe this is happening to me' and I love that. I get excited for them and their potential and wonder how it's going to go for them."

Bublé also spoke about his adoration for British songstress Adele.

He gushed: "I am a huge fan of Adele too. It's funny because we used to email each other and talk about doing something together before her debut album 19 came out, but the timing wasn't right.

The star added: "I remember writing to her saying, 'I can't wait for you to be the biggest singer in the world.' She wrote back very simple and sweet. I was really happy to see it happen for her - she has an incredible talent".