Five Turner winners call on National Portrait Gallery to cut ties with BP

Antony Gormley and Rachel Whiteread among nearly 80 artists stepping up campaign

Five winners of the Turner prize are demanding an end to BP's sponsorship of the National Portrait Gallery, stepping up the campaign against big oil's involvement in the arts.

Antony Gormley, Rachel Whiteread, Anish Kapoor, Gillian Wearing and Mark Wallinger are among a group of almost 80 leading artists, including winners of the BP portrait award, who have written to the gallery's director, Nicholas Cullinan, highlighting the company's role as one of the world's biggest fossil fuel producers and calling on him to cut ties. The group say it is necessary to ensure the gallery remains a "forward-looking institution that's on the right side of history".