An hour-long video of England football captain David Beckham sleeping has been unveiled at the National Portrait Gallery in London.

Entitled David, the video portrait is 67 minutes long and will be shown on a continuous loop for the next year.

"I wanted to create a direct, closely observed study," said artist Sam Taylor-Wood who created the footage.

"Filming while he was asleep produces a different view from the many familiar, public images."

The Real Madrid midfielder has been at the centre of media speculation about his marriage to former Spice Girls singer Victoria Beckham following newspaper allegations about his private life.

Sam Taylor-Wood, a contemporary of British artists like Damien Hirst and Jake Chapman, called the footage a "reverential and vulnerable image".

National Portrait Gallery director Sandy Nairne said Sam Taylor-Wood's image of Beckham was "compelling".

"All his famous goals are replayed on television all the time, and quite right too because they are wonderful," Mr Nairne said.

"But I think if you are going to try to get to the person, to the man, to him, you need perhaps a different approach.

"She gives us the chance as viewers to be very close to him, almost examine him, in a way that would not otherwise be possible."