According to reports, Tennant, who replaced Christopher Eccleston after the first series, has agreed to stay with the show until 2007. His sidekick Rose, played by Billie Piper, will also make an appearance, although the Daily Mirror is reporting that she has quit the series.
The news comes as the BBC unveiled a new campaign to promote the series, promising viewers: "Think you've seen it all? Think again." It was created by Red Bee Media and will launch this Saturday.
There is also a separate trail to promote what the BBC has dubbed "Tardisodes", which fans can receive by texting Tardis to 81010 or by visiting the BBC website. Tardisodes are extra footage and back story for characters that will not air on television. Each episode is between 30- and 60-seconds long.
Kerry Moss, drama marketing manager at the BBC, said: "Red Bee Media has created an exciting and engaging campaign that builds on the impact of the first series and Christmas special.
"The campaign speaks to child and adult fans alike, promising a brand new set of adventures with the Doctor and Rose."
The trails were directed by Sarah O'Gorman, written by Lisa Gledhill, produced by Jane Booth and overseen by creative director, Ruth Shabi.
In the second series of 'Doctor Who', viewers can look forward to a passionate kiss between the Doctor and Rose, as well as an appearance from comedian Peter Kay, who is to play a "cold and serious" character called Victor Kennedy.
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