However, while the rest of the band were charming and engaged with the crowd, Malik, famous for hitting the high notes, seemed “apathetic” and “struggled to smile even once”, said a Post reviewer who attended the concert.

Malik said in the statement that he decided to leave the band, which earned US$75 million last year according to magazine, to regain normalcy in his life.

“My life with One Direction has been more than I could ever have imagined. But, after five years, I feel like it is now the right time for me to leave the band.

“I’d like to apologise to the fans if I’ve let anyone down, but I have to do what feels right in my heart. I am leaving because I want to be a normal 22-year-old who is able to relax and have some private time out of the spotlight,” he said.

“I know I have four friends for life in Louis, Liam, Harry and Niall. I know they will continue to be the best band in the world.”

Now one man down, One Direction said: “We’re really sad to see Zayn go, but we totally respect his decision and send him all our love for the future. The past five years have been beyond amazing, we’ve gone through so much together, so we will always be friends.”

The remaining members, Louis Tomlinson, Liam Payne, Harry Styles and Niall Horan – all aged between 21 and 23 – said they would continue the world tour and would record their fifth album, due for release next year.

“The four of us will now continue. We’re looking forward to recording the new album and seeing all the fans on the next stage of the world tour,” they said.

One Direction were discovered when they auditioned separately on the television talent show in 2010, and were asked to form a boy group during the competition.

Performing better as a band, they were signed by one of the show’s celebrity judges, producer Simon Cowell, and have since topped the world music charts, smashed records and produced four highly successful albums.

Cowell said in the statement this morning: “I would like to say thank you to Zayn for everything he has done for One Direction. Since I first met Zayn in 2010, I have grown very, very fond – and immensely proud – of him. I have seen him grow in confidence and I am truly sorry to see him leave.”

Meanwhile, fans all over the world reacted with disappointment, shock, anger and despair.

"The sky without stars is like sleep without dreams ... One Direction without Zayn ... It's 'No Direction'," said one fan on Facebook.

Twitter was filled with messages such as: "Do not abandon us, I beg you" and "Please, please, please don't let it be true."

Others sent Malik words of encouragement. "You will always be loved by us and don't ever forget how much you mean to us," said a fan on Twitter. "Take care of yourself."