The 38-year-old Scot is tipped to play Bilbo Baggins in the big screen adaptation of JRR Tolkien's book.

Tennant leads a list of stars, including James McAvoy and Daniel Radcliffe, vying to play Bilbo. The film version of The Hobbit is based on Tolkien's children's book prequel to The Lord Of The Rings hit series.

Tennant is due to make his debut appearance at the world's biggest science- fiction and fantasy convention Comic- Con in the United States next week.

Rings director Peter Jackson is expected to announce his choice for the role when he attends.

Geoff Boucher of the Los Angeles Times said: "David Tennant just happens to be making his very first trip to the San Diego expo to promote Doctor Who, a television series that he will soon be leaving behind. Peter Jackson, the producer of the two-film Hobbit series that begins its theater run in 2011, is also slated to appear, and, well you can see the dot-connecting possibilities... I think Tennant would be exceptional in the role."

In the Lord of the Rings trilogy Bilbo Baggins was played by the veteran actor Ian Holm. But in The Hobbit he is a sprightly 50-year-old although hobbits live to be well over 150 years old.

Tennant is currently filming St Trinian's, The Legend of Fritton's Gold, and will be last seen as the tenth Timelord in a Christmas special.

Several members of the original cast are returning, including Ian McKellen as Gandalf.

Christopher Lee who played Saruman has announced he would like to come back, too. He said: "I've read the books time and again. Originally Saruman The White and the rest of the wizards, or the Istari as they call them, were immortal.

"When it all started, Saruman was the noblest, the finest, the bravest, the most dependable and reliable of them all, he was No1. But somewhere, somehow, and it was never actually explained, he turns.

"I'd be interested in seeing how that transition from good to evil occurred and, yes, of course I would return to the role if I was asked." THE DAILY TELEGRAPH