£25m Bacon leads battle of the art auctions

Study Of A Nude With Figure In A Mirror, painted in 1969, is expected to be the headlinegrabbing work in a week of auctions at Sotheby's from 5 February.

Other lots include an Andy Warhol portrait of Judy Garland and works by Picasso.

It will be the first time Sotheby's has held a contemporary art auction for more than a single day - reflecting the huge appetite for topend modern works in today's market.

On Monday 4 February, rival auction house Christie's will launch sales of its own.

Among its lots will be Lucian Freud's sketch of Bacon, part of a £3 million collection owned by the late artist R B Kitaj.

The sales will offer an accurate assessment of the contemporary art market, which has seen prices for top works quadruple in the past decade. Largely because of this, both Sotheby's and Christie's have enjoyed a hugely profitable year. Christie's boasted the highest half-yearly sales in art market history, while Sotheby's made its highest global turnover.

Both houses sold more than $1.7 billion (£858 million) of Impressionist and contemporary art in New York in November. In May, Bacon's Study From Innocent X went for $52.7 million (£26.6million) in New York, setting a record for the figurative painter.

Many industry watchers had predicted such a boom was likely to slow following the global credit crunch.

But Francis Outred, senior director of contemporary art at Sotheby's, said: "We've seen phenomenal growth in the contemporary market over the last four years - we felt the time had come for our sales to be presented on their own. Someone had to jump first.''

It will be the second time Sotheby's has tried to sell Study Of A Nude. Shortly after Bacon's death in 1992 it was put up for auction and was expected to fetch £1 million.

But problems with the international telephone exchange meant bids faltered at £680,000 and the painting was announced unsold. A private buyer purchased it later for about £700,000.

Dublin-born Bacon was thrown out of his home at the age of 16 after his father discovered his homosexuality. He began painting in London in 1929.

He died of a heart attack aged 82 in 1992, leaving an estate worth £8.5 million to his companion, John Edwards.