Katy Perry , Coldplay, Justin Bieber set to play at Capital FM Summertime Ball in London. Image credit: Facebook, Reuters

The secret for this year's Capital FM Summertime Ball is out and quite predictably the party will return with the most terrific line-up ever.

Nearly a dozen international celebrities are set to perform at the fourth edition of the Summertime Ball, set to be held at the Wembley Stadium in London on June 9, and the tickets will start selling from April 23 at 8:00 a.m.

Apart from Kelly Clarkson, Flo Rida, The Wanted, Example and Ed Sheeran, this year's ball will boast a spectacular line-up of A-list international singers.

According to the recent announcement by Dave Berry and Lisa Snowdon on their morning show, the 18-year-old heartthrob Justin Bieber is set to play at the festival this year, Daily Mail reported.

Well, it’s not only the teenager star who is set to exhilarate the eve, but the Hot n Cold Katy Perry and Coldplay are also in the list to enliven it.

“The secret’s out… the best ever line-up for the Summertime Ball is finally out there. It doesn’t get much bigger than this and I can’t wait to be there!” Berry said on his show.

Along with Perry, who also performed at its very first party in 2009, the event will also feature Usher, Jessise J and Pit Bull.

Tickets can be purchased online from www.capitalfm.com, of which a considerable portion will go for charity to London’s Help a Capital Child foundation.