LOS ANGELES (Reuters) - Boy band fever is storming the music scene in the United States, led by the Brits who are breaking away from the slick, squeaky-clean image of old as they battle to become America's newest pin-ups.

The five young men of The Wanted take on their baby-faced rivalsOne Direction with their self-titled debut EP released this week, following One Direction's No. 1 first album on the U.S. Billboard charts last month.

It's more than 10 years since New Kids on the Block, Backstreet Boys and N'Sync ruled the U.S. music scene and sent hordes of screaming young girls to record stores.

In Britain, boy bands have never gone out of fashion, although the new breed appears to have grown up.

If One Direction are the co-ordinated, clean-cut, media-savvy boy band, The Wanted are the rebellious antidote, uncensored by their team and left to win over audiences by goofing around with each other, and the media.

"We're different, we all play instruments, we don't dance and we don't dress very well," The Wanted's Tom Parker told Reuters.

The Wanted - Parker, Max George, Siva Kaneswaran, Jay McGuiness and Nathan Sykes, aged between 19 and 23 - were put together after mass auditions in the U.K. in 2009, and are managed by Scooter Braun, the mastermind behind Canadian teen idol Justin Bieber.

"All the acts that I manage are built organically and they all get to be exactly who they are," said Braun, 30, who encourages The Wanted to be open about drinking, partying and dating girls.

"I used to be a party promoter the last time boy bands were huge, and I knew a lot of those guys, and they like to party and drink and do all that stuff too. But they always had to hide it, and I think it's refreshing to see a boy band that doesn't hide it and that doesn't care," Braun added.

LADS HAVING FUN

One Direction - formed of Liam Payne, Harry Styles, Zayn Malik, Louis Tomlinson and Niall Horan, all aged between 18 and 20 - were put together in 2010, and are managed by Simon Cowell.

One Direction's image is more carefully groomed and choreographed in the vein of the boy band stereotype but that didn't stop a controversial romance between Styles and a British TV presenter 15 years his senior, prior to the band making their U.S. debut.

"We don't mind at all being called a boy band, we're just lads in a band. But I think we're trying to do something a little bit different...it's a bit more relaxed, lads having fun, we do what we want," said One Direction's Payne.

Both bands fall squarely into the pop genre, with One Direction embracing innocent, fun love songs such as with their lead single "What Makes You Beautiful," which peaked at No. 4 on the Billboard Hot 100.

The Wanted have taken a more adult route, with heavier dance beats and raunchier music videos such as their single "Glad You Came," peaking at No. 3 on the Billboard Hot 100 singles chart.

"Their music is really different to ours and I think anyone can see that, and you can like one or the other or both," said The Wanted's McGuiness.

"A lot of people expect boy bands to cater music exclusively to young girls...we accept that a lot of young girls do like us, but we respect their musical choice as much as we respect a 50-year-old dude," McGuiness added.

DIRECTIONERS VS. TEAM WANTED

The Wanted have received mixed critical reviews for their debut EP in the United States, released this week.

August Brown at the Los Angeles Times said that while The Wanted were "saucier and sleeker" than One Direction, their music wasn't "nearly as fun," while Maura Johnston at Rolling Stone said "their dance pop droops where it should bounce."

Devoted fans, known as "Directioners" and "Team Wanted," compete on Twitter to make the bands a trending topic, and have been a fundamental part in driving sales.

"As much as we don't try to be perfect all the time, we knew America had an idea of boy bands...we have to thank them because they welcomed us with open arms, and we could never have expected it," said McGuiness.

One Direction's first album, "Up All Night," sold more than 176,000 copies in its first week, entering the Billboard 200 album chart at No. 1 and making history as the first UK band to debut at the top with their first album.

The Wanted also look set to chart high, currently at No. 7 on iTunes.

One Direction has more than 5 million fans on Facebook and 3.2 million "Directioners" following on Twitter, while The Wanted have more than 1.6 million fans on Facebook and 500,000 Twitter followers.

Parker from The Wanted called the adulation "pretty weird at times" and Horan from One Direction admitted he gets a "bit scared" when their female fan base are driven into a frenzy.

Manager Braun brushes off critics who dismiss boy bands as mere manufactured creations.

"People forget that the Beatles were once a cheesy boy band - that's what America other than the teenage girls thought. But then they kept making great records...when you make great songs, everyone else just shuts up," said Braun.

(Reporting By Piya Sinha-Roy, Editing by Jill Serjeant)