Justin Bieber claims he went on 40 minutes late -- not two hours -- for his gig at London's 02 Arena Monday, then apologizes to "anyone we upset" with the delay in a new set of tweets.

As we previously reported, the Beauty and the Beat singer was booed like a war criminal when he emerged for his show Monday, as many parents in attendance said they had to take their tired kids home before the superstar singer emerged onstage at 10:40 p.m. local time -- two hours and ten minutes after the advertised start time of 8:30 p.m.

The 19-year-old pop star, via Twitter, addressed the budding controversy with a jumbled, slightly defensive account of the night's timeline. (Note: The spelling and grammar have not been changed from Bieber's original posts.)

He wrote, "Since i have been here it hasnt been easy with the press at times but I have loved it. so let me say this... last night i was scheduled after 3 opening acts to