Singer George Michael's decision to quit pop music has shocked Robbie Williams who was looking forward to record a duet with the former Wham star.

Williams is currently preparing to start recording a new album of collaborations and admitted he wanted to secure the services of the "Fast Love" singer for the record's big single, Internet portal femalefirst reported.

Robbie, 31, first asked Michael to perform on the album when the pair met earlier this year during filming for a special episode of cult British comedy "Little Britain" for TV telethon "Comic Relief".

However, Robbie's plans were left in tatters when the 41-year-old Michael revealed he was turning his back on music indefinitely.

The decision has left the "Angels" singer with the headache of finding another big name artist for the album's showpiece. Robbie said: "I'm gutted. I really wanted to duet with him on my album."