Former Manchester United and England defender Rio Ferdinand said Thursday he was "disappointed" after being refused a professional licence by British boxing authorities.

Ferdinand, coached by former WBC super-middleweight champion Richie Woodhall, was being backed by betting company Betfair as part of the "Defender to Contender" challenge.

"Having been training four to five times a week since announcing the aim of achieving a professional boxing licence and stepping into the ring, it is with a heavy heart that I am hanging up my gloves," he posted on Facebook.

"Despite having never felt better physically or mentally, after notifying the British Boxing Board of Control of my intention to apply for a licence, I have received confirmation that they would not be reviewing my application at this point in time.

"To say I'm disappointed by this decision is an understatement," said the 39-year-old, who also played for West Ham, Leeds and QPR.

"Boxing is a physically tough, demanding and dangerous sport," added the former centre back, who won six Premier League titles and the Champions League during his time at Old Trafford.

"I always gave it my utmost respect and never underestimated how difficult it would be. I wanted to show people that it's OK to have a goal and strive to reach it. It's important to approach everything with success in mind, and to give it your all, but sometimes things work against you."

Former England cricketer Andrew Flintoff changed sports and won his only professional fight over four two-minute rounds against Richard Dawson in 2012.