Justin Bieber has apologised for appearing on stage late at his O2 arena show last night.
He told fans on Twitter: "I was 40 min late to stage. There is no excuse for that and I apologise for anyone we upset."
Justin denied he was two hours late, claiming he was only supposed to appear at 9.35pm - making him just 40 minutes late.
Fans at the show booed during their long wait and many had to leave during the show, otherwise they would have missed their trains home.
The O2 arena has also apologised for the late start.
Justin has now promised: "Tonight we will run on time and look forward to putting on an amazing show for everyone in attendance."
If you were at the concert and want to try and obtain a refund, you can get in touch with the O2 contact centre on 020 8463 2000 or email email@example.com
Does it matter that Bieber was late for his fans?
Would you have waited or would you have been booing when the star didn't turn up when you expected him to?
Sorry this chat page has now closed, but below are some of your comments.
"I think it is unacceptable. People paid good money to watch him. Everyone should either be offered a free ticket to another concert or their money back. It's not fair for people to turn up and not get what they expected."
"I travelled all the way down to London to see Justin Bieber! I just can't get enough of him. He is really nice and his hair is adorable! I had to wait two hours and it was definitely worth the wait, when people booed I just thought that the fans weren't true Beliebers, when he came on I screamed and jumped about in joy!"
Josie, Rossendale, England
"If I went to a concert and he was over TWO HOURS late I would demand my money back. I don't think the 02 is to blame, Justin Bieber himself is to blame. He should have apologised and gave an explanation. I was planning on getting tickets to his concert this year but ended up not being able to but after hearing this I'm glad I didn't because it would've been a waste. Also, his fan base is from the ages of like 5 to 18 or older, it's a lot and the little kids must of been so tired or upset at the fact that they couldn't have seen his whole set because he was late and they had a train to catch. He needs to step up his game and be more responsible because otherwise he will lose fans."
Racheal, Coventry, England
"I think he's really selfish to waste his fans time and money. I'm not a fan, but if I was I wouldn't be after that. He needs to respect this fans. He's nothing without them."
Mandy, Manchester, England
"I was actually there. It was amazing to start off with, with all the opening acts but it started to turn into a joke when we had to wait so many hours for Justin and no one knew what was going on. Seeing crying girls leaving the 02 without seeing Justin which they paid for. But when the countdown started, the boo's turned to screaming girls and it was totally worth the wait, Justin Bieber did his fans proud. Amazing night."
Zia, Weston Super Mare, England
"I was one of the fans that booed Justin Bieber because he was late for about two hours. I was very bored when he came on and really angry as well because I missed my train."
Hana, London, England
"I would boo him because he should be there on time. I would ask for my money back and he should apologise as well."
Emma, Oxford, England
"He shouldn't have fans, he doesn't care about them, if he cared about fans he wouldn't be late, but he doesn't, he only cares about the money."
Josyln, Wiltshire, England
"I wouldn't blame him for going on stage late because if you're going to perform, you do get anxious in front of an audience and try to postpone as much as possible."
Aidan, London, England
"Don't boo, he was only late, not the end of the world, at least he still performed and you still got to see him."
Amber, Manchester, England
"I was there last night and there was a lot of booing, but everyone screamed when he finally came on."
Khaya, Essex, England
"I was at the Nottingham concert, I took a two hour train from London to get there and he was around an hour and a half late, although I did stay as my mum paid £90 per ticket I didn't get back to the hotel until one in the morning."
Hayley, London, England
"I think he shouldn't of got booed. It's not his fault that he was late! I'm going to his concert tonight so even if he is late I won't boo him.
Amelia, Hertfordshire, England
"Justin had a perfectly good reason for being late but he just hasn't had time to explain it yet. i would never have booed him and walked away. So far he has had a hard week and said that he had the worst birthday ever. He needs our support!!!"
"I wouldn't have booed him, I'd just be thankful I saw him because there are some people who didn't get a chance to get tickets."
Emma, Cheshire, England
"I would have been one of the people booing him because he gets so much support from his fans, he should give them something back by at least arriving on time!"
Rachel, Clackmannan, Scotland
"I love Bieber, he's a talented singer, but I would not wait 2 hours for him in fact I think I would boo him."
Bethany, Maidstone, England
"I'd have waited all that time for Justin Bieber, even if it meant missing the train home. Those people who booed him should be ashamed of themselves. They should be privileged to even be there and that he turned up."
Oriann, Devon, England
"I would stay up as late as I could to see him. I'm a true Belieber!"
Daisy, Lincoln ,England
"I think that I would cheer because you enjoy it more when you wait for it."
Taylore, County Durham, England
"I went to Nottingham on Saturday 2nd March. Justin was over one hour late coming on stage. My sister complained to one of the stewards who said he would be playing the full set and going over the 11pm curfew, but his management would have to pay a fine for over-running the curfew. We didn't get home until 1am in the morning but luckily it was a weekend concert. We were very disappointed that there was no explanation for his late appearance."
Eleanor, Derbyshire, England
"I think that he should apologise as people paid a lot of money to see him. I wouldn't have waited for him."
Posy, Brighton, England
"I wouldn't have minded if he was just half an hour late to his concert, but two hours? That's just pushing it! I wouldn't have stayed around long enough to wait for him to come on. I think I would probably have just gone home after an hour. I mean, it's his concert. People are there just for him. Why would he do that?!"
Rhiannon, Walsall, England
"We waited at the parking place where he would arrive for five hours to see him - I would wait all day to see Justin perform."
Rebecca, Glasgow, Scotland
"I wouldn't boo him I love him sooo much."
Melissa, Darlington, England
"I would have waited all night if it meant seeing Justin in concert. I'm a Belieber forever and would do anything to see him."
Becky, Burnley, England
"I wasn't at the concert but even if I was I would have stayed and not booed him. I am a true Belieber, and true Beliebers wouldn't boo their idol."
Tallulah, London, England