Frustrated fans of US singer Bruno Mars are demanding refunds after a problem with a ticket scanner saw hundreds locked out of his sold-out gig in Birmingham last night.

Fans, who had paid between £43 to £85 to see Mars on his 24K Magic World Tour, didn't get into the Barclaycard Arena until after 10pm - and by 10.50pm the show was over.

Many took to Twitter to vent their frustration. One mother said she had travelled for hours to celebrate her daughter's 16th birthday, only to miss the gig completely.

"Dear @BrunoMars devastated 16-year-old birthday girl & mum travelled hours for birthday treat to @BcardArena Queued hours - no entry," @evmore girl tweeted.

While @PatersonKaren said: "Can't believe someone is tweeting @Brunomars concert footage on @BcardArena acct but won't respond to customers. Do you know what twitter is?

Bosses at the Barclaycard Arena have apologised to fans and say they are putting plans in place to prevent a similar thing happening again.