The 41-year-old former Grange Hill actor, who has been in showbiz since childhood, admitted problems with substance abuse as a result of a knee operation two years ago, which led to depression and chronic pain.

McPartlin told the Sun On Sunday that the knee surgery left him in “agony”.

He was reported as having cried as he told his wife Lisa Armstrong and presenting partner Declan Donnelly of his dependency on drugs and alcohol.

The presenter struggled with alcohol dependency

While the star – who is worth a reported £60m – is said to regularly enjoy a drink with co-star Declan Donnelly.

McPartlin also developed a dependency on painkiller Tramadol - a Class C opiate-based drug which is regularly prescribed for individuals suffering from extreme pain.

Having checked into rehab, McPartlin told the Sun on Sunday: “I feel like I have let a lot of people down, and for that, I am truly sorry.

“I want to thank my wife, family and closest friends for helping me through this really difficult time.”

Friends of McPartlin, who lives in Chiswick, West London, are said to have voiced worries over McPartlin combining Tramadol with alcohol after boozing sessions.

A friend told the Sun on Sunday: "Ant would often continue drinking alone at home afterwards. Part of it was that the alcohol helped numb the physical pain he has been enduring.

He is no longer as fit as he was and is less able to cope with the rigours of filming.

“During the finals of BGT Ant’s appearance was the subject of discussion among the backstage crew. It was clear he was really struggling behind the scenes.”

McPartlin and Donnelly have a rigorous work schedule, fronting both Britain’s Got Talent and I’m a Celebrity… Get Me Out Of Here! the demanding nature of which is said to have led to issues with anxiety.

The star decided to go public to help others

The presenter told the Sun on Sunday that he wanted to speak out about his struggles in order to help other people going through similar struggles.

He said: “I’ve spoken out because I think it’s important that people ask for help if they’re going through a rough time and get the proper treatment to help their recovery.”

Celebrities have supported McPartlin’s decision to voice his struggles.

Apprentice presenter Alan Sugar wrote on Twitter: "Very brave Ant to go public. This is the first stage of the road to recovery. All the best Ant it, will all be sorted for sure @antanddec

Good Morning Britain presenter Piers Morgan added: "Few nicer people in showbusiness than Ant McPartlin. Wish him all the best as he sorts himself out."