Justin Bieber due to perform despite collapse - venue

LONDON, March 8 (Reuters) - Canadian pop star Justin Bieber is expected to perform the last of four gigs at London's O2 Arena on Friday despite collapsing on stage on Thursday and later going to hospital, a spokeswoman for the venue 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 show is still scheduled to go ahead this evening," said a spokeswoman for the O2 Arena.

Bieber's representatives, most of whom are based in the United States, did not immediately reply to emailed questions about the "Boyfriend" singer's health.

As well as messaging his 35 million Twitter followers overnight that he was "getting better", Bieber also posted a picture on Instagram of him lying shirtless on a bed, wearing earphones and smiling.

Bieber had not been suffering from any health issues prior to the show, his spokeswoman said on Thursday.

It was not the first time Bieber had collapsed on stage. He previously 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. (Reporting by Mike Collett-White; Editing by Kevin Liffey)