David Haye has announced his retirement from boxing at the age of 37.

The former WBA heavyweight champion insisted he would stop fighting if he again lost to Tony Bellew in their rematch last month, and having shown significant signs of decline before being stopped in five rounds, he has confirmed he no longer plans to fight on.

Haye first announced his retirement in October 2011 on his 31st birthday, before a lucrative grudge match with Dereck Chisora the following summer tempted him to return.

He was also advised to retire following surgery on his right shoulder in November 2013, but returned in January 2016 to secure two unremarkable victories and then suffer his third and fourth professional defeats, both against Bellew.

“Thanks to boxing, I have been able to live my unencumbered childhood dream,” Haye said in a statement.

“I became the first ever British boxer to unify the cruiserweight division. I then achieved my childhood dream when I beat WBA heavyweight champion of the world Nikolai Valuev, the ‘Beast from the East’, in a real life ‘David and Goliath’ match.

“Lifting that world heavyweight championship meant I’d fulfilled a promise I’d made to my mum, Jane, at the age of three. It also meant I was the second boxer in history – after Evander Holyfield – to win world titles at cruiserweight and heavyweight. That was an incredibly proud moment.

“In the end, what 20,000 fans inside London’s O2 Arena witnessed was me giving 100 per cent effort (against Bellew) but performing way below world level."

However, there was one part of the statement that stunned fans, even ones that consider themselves die-hard David Haye fans.

The Hayemaker underwent spinal surgery in 2015, and in the statement, the veteran boxer revealed just how serious the operation was.

“The biggest physical challenge I had to face, however, was a spinal surgery in March 2015,” he wrote.

“I herniated a disc in my lower back 10 years ago and years of intense training wore this disc away. This caused fragments of disc to push into my spinal nerve passage, resulting in chronic pain and loss of function in both legs, and an operation was required to put a two-centimetre metal cage between two vertebrae and implant two metal rods with screws and bone grafts to fuse it all together.

“I went into surgery 191 centimetres tall and came out 193 – not a bad silver lining! – but literally had to learn to walk again.

“This made my comeback fight against Mark de Mori [in January 2016] all the more meaningful, as it was only 10 months after such intrusive spinal surgery [as well as being my first fight in four-and-a-half years].

“Ultimately, this was one battle I had to fight in private, and it’s only because the process was recorded for a documentary that people will one day be able to grasp the severity of the situation.”