Tennant blames Tate for "quitting" rumours
Tennant, speaking at the launch of the Christmas episode, said: "Catherine Tate stitched me up good and proper."
"I started getting all these phone calls on Saturday lunchtime saying apparently you're leaving Doctor Who," Tennant told the BBC. "Catherine Tate's just announced it on Radio 2 - thanks Catherine!"
He added: "I said to her on Monday morning did you know you've caused a minor diplomatic incident? She was completely oblivious that the phone had been ringing off the hook."
"I'm doing four more specials and beyond that no one's asked me to make any decisions and I'm quite happy to be enigmatic for as long as possible," he said.
The audience included Work and Pensions Secretary Peter Hain who told the BBC afterwards: "It was absolutely awesome. Millions are going to be glued to their TV sets."
Doctor Who writer and executive producer Russell T Davies said: "I'm delighted with the next series, we're doing stuff we've never done before and it's bigger and better than before."
He said Kylie Minogue was keen to do more acting again.
"She did this because I think that's the way her thoughts are heading. She's missed it and fancied that discipline. I'd cast her again like that," he said.
Asked by a child in the audience whether evil Dalek creator Davros would be resurrected for the new series, Davies said: "I don't know. I'm as in the dark as you are. Would you like us to?"
Amid much laughter, he stroked his chin and added: "I'll see what I can do."