The first episode of the new series of Doctor Who has mysteriously appeared on the internet. The 45-minute episode is called Rose - after the Doctor's new assistant, played by Billie Piper. It is unclear whether the show was leaked accidentally or as part of a devilish viral marketing campaign. The press launch for the series is being held in Cardiff this evening.

The BBC insisted it was "a significant breach of copyright which is currently under investigation". It urged viewers to wait for the finished episode to be broadcast. The broadcaster blamed a co-production partner for the leak.

The episode is available on Bit Torrent and other file sharing networks.

Rumours are the 13-part show will be broadcast from 26 March. The speculation was apparently confirmed on BBC Radio 4's Front Row arts show last night.

It has also emerged that star of the show, Christopher Ecclestone, emailed the new series' developer and chief writer, Russell Davies, to ask if he could play the Doctor. ®

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