AN ANONYMOUS BIDDER has paid €12.8 million (£10.8m) for a previously unseen self-portrait by legendary pop artist Andy Warhol at an auction in London.

The red-and-white square portrait – which features Warhol’s face in half-shadow, and measures six feet on each side – dates from 1967, and had only recently been rediscovered by an authentication board which verifies the artist’s work.

The portrait had been in private collection since 1974, the Daily Telegraph reports, and had last been seen in public at the Museum of Modern Art in New York (MoMA) in 1991 for an exhibit to mark the artist’s death two years earlier.

Other works from the series of 11 portraits on display in Munich, San Francisco and in the Tate collection in London. The sale price more than doubled the reserve price.

The image depicted in the portrait, which is believed to have been completed in 1967, was used in smaller works the previous year.

A spokesman for Christie’s, who oversaw the auction, told Sky News that it had been “an incredibly exciting journey to work with a previously unknown work by Andy Warhol, particularly one with such historic importance.”

The sale was part of a larger sale of contemporary art which brought in almost €73m; the Wall Street Journal reports that the buyer was US dealer Larry Gagosian, who secured the painting on behalf of an apparent telephone bidder.