London's Tate Britain gallery has been invaded by a group of green campaigners protesting at a sponsorship deal with the oil company, BP.
Protesters faked their own deaths on the gallery's steps
A dozen campaigners wearing anti-BP slogans protested at a display of Turner watercolours.
Security officials failed to stop the protesters from collapsing in a pile and pretending to be dead.
The Tate said that the support given by sponsors is essential, because of scarce funding.
Campaigners from London Rising Tide handed out leaflets at the exhibition.
A spokesman, Iggy, said: "It's outrageous that BP should be trying to improve its reputation by sponsoring these beautiful landscapes - landscapes which these days are being polluted by oil companies.
"BP destroys beautiful places, spilling oil in Alaska and contributes massively to global warming.
"The Tate should consider the ethics and moral behaviour of its sponsors."
The Tate said sponsors' money was crucial
BP's former chief executive, Lord Browne, was appointed a trustee of the Tate Gallery last year.
BP was fined $373 million in the United States for fraud and environmental crimes, relating in part to an oil spill in the Alaskan wilderness. The Tate said support given by organisations was 'extremely important', because funding is scarce.
A spokesman said: "The Tate Trustees agreed a sponsorship policy in 1991 and regularly review it.
"BP, who have worked with Tate for 15 years, fit within these guidelines and their support has been instrumental in helping Tate develop access to the Tate Collection and to showing work by a wide range of artists."
BP refused to comment on the protest.