Russell T Davies is to write a sci-fi paranoid thriller in a major new drama commission for BBC THREE, it was announced today by Stuart Murphy, Controller of BBC THREE.

Torchwood is a 13-part drama series aimed at a post-watershed audience and has an organic link to Doctor Who.

"Torchwood is a British sci-fi paranoid thriller, a cop show with a sense of humour," says Russell T Davies.

"It's dark, wild and sexy, it's the X Files meets This Life. It's a stand-alone series for adult audiences which will have its own unique identity.

"I have just begun working on the scripts with a team of writers and cannot wait to see the results."

Set in modern-day Cardiff, Torchwood stars John Barrowman as Captain Jack from Doctor Who; it's in the Christmas special and second series of Doctor Who that the story of Torchwood - a renegade group of investigators - is seeded.

However, no stories will cross over between Torchwood and Doctor Who.

The drama series is produced by BBC Wales and will be transmitted later next year.

Stuart Murphy says: "The renegades investigate human and alien crime, as well as alien technology that has fallen to Earth.

"Torchwood is sinister and psychological - Russell was really keen to play with your head - as well as being very British and modern and real.

"But at the centre of the drama are warm, human relationships and the overcoming of adversity."

John Barrowman says: "I'm absolutely thrilled about Torchwood. It's going to be a dark, wild and sexy roller-coaster ride.

"Working again with Russell T Davies, Julie Gardner and the BBC is like hooking up with family again. I can't wait to explore Captain Jack even more."

Murphy adds: "Torchwood is a massive coup for BBC THREE, and a major commitment - it's the biggest drama we've ever had on the channel.

"It introduces a different tone into our drama, just as Russell's Casanova earlier this year brought warmth and humour.

"He's an absolute genius - you look at what he has done with Doctor Who - we said to him, 'What would you do with a post-watershed sci-fi?' Its subject and tone is a perfect fit for BBC THREE."

Filming on the 13 self-contained episodes will begin early next year in Cardiff; other writers so far confirmed include Chris Chibnall and PJ Hammond.

The executive producers are Russell T Davies and Julie Gardner, Head of Drama in BBC Wales.

Torchwood follows the success of Casanova (which attracted a record audience for a drama on the channel), Bodies, Conviction and Outlaws, with which the channel has begun to establish a reputation for cutting-edge British drama.

Torchwood is a BBC Wales commission for BBC THREE.