Justin Bieber has become the first Twitter user to reach 40 million followers.

The 'Beauty And A Beat' hitmaker - who joined the micro-blogging site in 2009 - has beaten other stars, including Lady Gaga and Taylor Swift, to the milestone with his @justinbieber account.

He wrote: ''#40millionstrong'' before later adding ''#40millionBeliebers - thank you. I love u. #grateful (sic).''

Justin's Twitter record comes soon after 'White House Down' actor Channing Tatum revealed he was worried about the 19-year-old singer.

The 33-year-old actor thinks the 'Baby' hitmaker - who was discovered at the age of 14 - found fame too young and hopes he doesn't go off the rails like many child stars do.

He said: ''I do believe that whatever age you become famous, you end up staying that age.

''I worry about Bieber, man. That kid's wildly talented. I hope he doesn't fall down into the usual ways of young kids because it' so hard for someone to be responsible when they're not asked to be.''