Canadian singer Justin Bieber performs in a concert at the Manchester Arena in Manchester, northern England, February 21, 2013. [Photo/Agencies]

Canadian teen pop star Justin Bieber collapsed on stage from shortness of breath during a performance in London on Thursday, representatives for the singer said.

"(Justin's) heading to the doctor now," Bieber's spokeswoman Melissa Victor told Reuters at midnight local time. "He fainted and took a 20-minute reprieve and was given oxygen."

Related: Actress' death at 27 raises cancer concerns

Bieber, 19, returned to the stage after the break to finish the show, and his representatives said he was OK.

"Justin got very light of breath, the whole show he has been complaining," Bieber's manager, Scooter Braun, told the crowd in several amateur videos posted on the Internet. "He's backstage with the EMTs and the doctor."

Bieber's spokeswoman told Reuters that the "Boyfriend" singer ignored doctors orders and returned to the O2 Arena stage to finish the performance.

The Canadian singer had not been suffering from any health issues prior to the show, the spokeswoman added.

Fans had already started circulating the hashtag "#justintakeabreak" on Twitter after news of his collapse spread on the social network.

Bieber was performing for the third out of four nights at London's O2 Arena as part of the European leg of his sold-out "Believe" world tour.