A screenprint of model Kate Moss by artist Banksy fetched three times its estimated price at an auction last night devoted solely to street art.

The work, a pastiche of Andy Warhol's iconic portrait of Marilyn Monroe, sold for £96,000 at Bonhams in London.

The Bristol-based artist's Laugh Now, a stencil image of a monkey wearing a sandwich board which was expected to sell for £150,000-£200,000, went under the hammer at £228,000.

The auction signalled another step towards the mainstream for the genre, with 75 pieces of "urban art" in the catalogue.

Spray-paint and stencils featured largely in the works on sale, and many began life as street graffiti before being transferred to canvas.

Gareth Williams, an urban art specialist at Bonhams, said last night: "We are delighted at the results of this sale.

"The Urban Art sale is unique in terms of the unprecedented media coverage, the phenomenal level of interest from buyers before the sale and the way that it has captured the public imagination.

"The results achieved are consistently strong across the board not only for blue chip artists such as Banksy and Keith Haring but also for emerging names whose works have not previously sold at auction.

"This shows that there is a growing market place for works of this nature and we are delighted to have held this pioneering sale."

He said earlier: "By definition (urban art) is an ephemeral art form, often disappearing as fast as it appears.

"By transposing their images from street wall to canvas, urban artists are now creating a permanent legacy without compromising the vitality of their art form."

More than 500 people gathered at the New Bond Street saleroom to see works by artists including Haring, an American who rose to fame for chalking hundreds of images on the New York subway in the early 1980s, go under the hammer.

Nick Walker's Moona Lisa, which had an estimated price of £3,000 to £5,000, fetched £54,000 while another work by Banksy, Di-Faced Tenners, fetched £21,000, double its estimated price.

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