A drawing by Michelangelo which lay unrecognised for more than 250 years was sold today for nearly £6 million, auction house Sotheby's said.

The study of a Mourning Woman was bought by British fine art dealer Colnaghi in a sale which could see the work leave the country.

It will go into the company's stock and offers will be considered from buyers the world over.

The work, the second major Michelangelo drawing to be discovered in the past 25 years, shows a three-quarter length side view of a woman with her face obscured by the folds of a heavy cloak.

It was discovered by Sotheby's expert Julien Stock in the late 1990s, in a library at the stately home Castle Howard, in North Yorkshire.

Colnaghi's managing director, Jean-Luc Baroni, said after today's sale in London: ''We bought it for stock and we hope we will sell it. We think we have a very good chance. We do not have a client in mind.

''When you find something that has never been seen it is just fantastic. It is not just a little drawing it is an important piece of his work.''

The drawing had a powerful attraction on art-lovers, he said, adding: ''Every time you walk by you are hit by it. It draws you closer. You really have to enjoy the drawing.'' Only three major drawings by the Renaissance artist, other than those in the Royal collection, are currently known to be in private hands.

Another Michelangelo drawing, a large study of Christ and the Woman of Samaria, was sold at Sotheby's in New York in 1998 for just under 7.5 million dollars (£5.3 million).

Henry Wyndham, chairman of Sotheby's Europe, said he was pleased with the sale price for the Mourning Woman, which fell between the estimate of £5 million and £7 million.

''It is a wonderful price for a beautiful drawing. Considering we did not know of its existence until a couple of years ago it is a bonus,'' he said.

The drawing belongs to a small group of large-scale figure studies by Michelangelo, which the artist is thought to have made early in his career, between about 1495 and 1505.

It was sold for £5,943,500 by Sotheby's on behalf of the trustees of the will of the late Lord Howard of Henderskelfe.