Union J were mobbed by over 2,000 girls at a concert in Portugal.

The 'Carry You' singer's growing fan base looks set to rival fellow 'X Factor' boy band One Direction, as they needed a team of security guards to help control the screaming fans who turned up to watch them support Selena Gomez earlier this month.

Band member JJ Hamblett exclusively told BANG Showbiz: ''When we arrived there it was crazy, there was like 2,000 girls already there just screaming, we had people there with us to help hold them back and stuff.''

It seems the group - which is also made up of George Shelley, Josh Cuthbert and Jaymi Hensley - haven't quite got used to being fame since their stint on 'The X Factor' in 2012, as JJ admits the show and subsequent attention has been a little ''overwhelming''.

The 25-year-old heartthrob said: ''Honestly we have never experienced anything like that before. To know that overseas there was that kind of reception for Union J it was absolutely amazing. [My highlight was] hearing them sing 'Carry You' because it's the first time we've ever really performed outside of the UK so hearing that was overwhelming.''

JJ - who is expecting his first child with his dancer girlfriend, Caterina Lopez - could get used to globe-trotting and is keen to back to Portugal.

He said: ''Hopefully, we would like to go back there soon.''

Union J launched their first official memoir 'Our Story' at Waterstone's in the Bluewater shopping centre in Kent, England, on Thursday (26.09.13).

'Our Story' is available to buy now.