Billie Piper has quit her role as "Doctor Who" sidekick Rose Tyler before the second season of the series starts reports The Mirror.

The 23-year-old star told producers she did not want to become typecast as they begged her to stay for a third series of the hit show. BBC chiefs have now launched a secret bid to find her replacement.

The choice mirrors Christopher Eccleston's decision to quit his role as the Doctor before the first series even went out (Eccleston played the title role for the 12-episode first season run). Piper did stay on to film the second season with new Time Lord David Tennant and a Christmas special.

A source says: "The BBC are auditioning other girls to take over. They want to have the next actress all lined up when they announce Billie's departure. They are quite miffed about her decision. The casting people have been conducting secret auditions with a small number of actresses and keeping it very, very quiet. They are after a relative newcomer so this is the role which puts her in the public eye".

Meanwhile, the BBC has revealed the new look for the Doctor's old foe 'The Cybermen' who are the key bad guys for the second season. A large picture of this new look can be found by clicking here.

Thanks to 'Wintermute'