Who blacked out Banksy's mural?

An inquiry has been launched into who painted over a work by the self-styled guerrilla artist Banksy, which was spray painted on a wall near a London Tube station.

London Underground workmen have denied they were responsible for painting over the spray-painted mural of John Travolta and Samuel L Jackson which has become one of the artist's most popular works.

The mural near Old Street station, depicting the Pulp Fiction actors holding bananas instead of guns, was blacked outto the bafflement of his fans. Transport for London confessed to having covered the mural in thick black paint last week, but after re-interviewing its anti-graffiti teams, it found they were not responsible. It said it suspected someone was "out-Banksying Banksy", and now there is a suspicion that rival artists may have painted over the mural.

The identity of Banksy, whose work is owned by Brad Pitt and Jude Law, has never been confirmed, but a friend of the artist said the work would be worth £300,000 if it had been removed from the wall and sold. The space has now been covered with fresh graffiti, saying "come back".