Sotheby’s and Christie’s, the two main art auction houses, together sold a record $12.5bn in artworks last year, a rise of more than 40 per cent as the art market showed no sign of slowing.

Both groups said they expected to set more records at the next big auctions, the February Impressionist and Modern sales in London. Christie’s has said it expects its sales there to be about $560m, almost 40 per cent higher than last year.

Sotheby’s, which also has a strong line-up, has provided a record guarantee for a work by Francis Bacon, Study of a Nude with Figure in a Mirror. It said it would sell for at least $35m.

Sales of post-war and contemporary art – which includes Bacon – were especially strong last year. Christie’s lifted its sales in this area by 75 per cent, to $1.56bn, during the year.

Christie’s last year sold $6.3bn in artworks, a 36 per cent rise on the previous year. Private sales almost doubled to $542m, a reflection of the way the auction houses increasingly are taking on the role of dealers in finding buyers for artworks where a seller does not want to go through the auction process.

Christie’s said it was more profitable than Sotheby’s, but did not disclose its profit. The group is privately owned by French billionaire François Pinault. Sotheby’s, which is publicly traded, will in late February release its profit for 2007. Its net profit for the nine months to September was $111m, triple that of the previous year.

Sotheby’s said it lifted sales last year by 51 per cent to $6.2bn, closing the gap on its rival. Sotheby’s sold far fewer lots, reflecting its move away from small-ticket items in favour of more lucrative artworks.

Sotheby’s said this week it would buy back its New York City headquarters for $370m from a company controlled by Aby Rosen, the developer and art collector. The group agreed to sell it in 2002, when it was strapped for cash after the anti-trust scandal and fines.

Sales in the Middle East, Asia and Russia continued to be strong for both auction houses, adding impetus to a market historically dominated by Western money and tastes.

Bonham’s, the third-largest auction house, which is making a big push into the US, said its sales rose by 25 per cent to $590m last year. The group has grown rapidly through acquisitions and said it was open to making another acquisition if the opportunity presented itself.