LONDON (Reuters) - Canadian pop star Justin Bieber was feeling "a little under the weather" on Friday, a day after collapsing on stage, but plans to perform the last of four concerts at London's O2 Arena, a spokesman said.

Bieber, 19, suffered from shortness of breath during his performance and, after a 20-minute break during which he was given oxygen by doctors, he completed his set. The "Boyfriend" singer was later taken to the hospital.

"Justin has been released from the hospital after a check-up and while he's feeling a little under the weather, he's planning on going ahead with tonight's show," the spokesman said in an emailed response to questions.

Bieber messaged his 35 million Twitter followers overnight that he was "getting better" and posted a photograph on web service Instagram of him lying shirtless on a hospital bed, wearing earphones and smiling.

The pop singer was not suffering from any health issues before the show, a spokeswoman said on Thursday.

It was not the first time Bieber has collapsed on stage. He suffered concussion during a concert in Paris last June after falling into a glass wall.

The London leg of Bieber's sold-out "Believe" world tour has not been without its problems.

On Tuesday, the first night at London's O2 Arena, Bieber angered fans by turning up on stage nearly two hours late, blaming technical issues for the delay.

After completing the London part of his tour, he is due to travel to Lisbon for two gigs on March 11 and 12.