Bernard was picture editor of the Sunday Times for several years

The 1992 portrait of Freud's friend Bruce Bernard - estimated to fetch �5m - was part of a sale of post-war and contemporary art at Christie's.

Francis Bacon's Two Men Working in a Field sold for just over �5m. Andy Warhol's Three Marilyns went for �5.6m.

A self-portrait by Bacon is expected to fetch up to �12m at a Sotheby's auction, also in London, on Thursday.

Another Bacon, Landscape with a Car, was bought for �4.2m at the Christie's sale.

'Significant portrait'

Charles Dupplin, art expert at specialist insurer Hiscox, said the price for Freud's Bruce Bernard portrait was no surprise.

"This work by Freud, thought by many to be Britain's greatest living artist, always looked like a record breaker.

"Apart from the general trend for contemporary art going up in value, this is a particularly special and significant portrait of a close friend of Freud," he added.

Bernard, who died in 2000, was a picture editor and writer of books on photography and painting.

The sale comes during a big week for art auctions in London - on Tuesday, Claude Monet's masterpiece Nympheas sold for �18.5m at Sotheby's.

Another Monet sold for just under �18m, more than twice its estimated price, at Christie's on Monday.

Art experts estimate that this week's London sales could generate almost �500m.