The all-women Orange literature prize is still needed, despite women winning prizes in fair competition with men, the organisers have said.

The Orange prize longlist, published yesterday, includes Anne Enright’s The Gathering, which won the unisex Booker a few weeks ago. In the past two years, women have won both the Booker and Costa literary awards.

The novelist A. S. Byatt told The Times that the Orange was a sexist prize, saying that she was so critical of what it stands for that she forbids her publishers to submit her novels for consideration. “Such a prize was never needed,” she said, noting that many works of literature were by women.

John Sutherland, the academic, said that ghettoising women writers did them more harm them good. Anita Brookner, a Booker winner, has dismissed positive discrimination and is also believed to have declined having her novels entered for the Orange.

Harriet Hastings, project director of the Orange prize, shrugged off the criticisms, maintaining that it was international and had no need to justify its existence: “Although major prizes have been won by women, the value of the Orange is as a celebration of women’s fiction.”

She dismissed the suggestion that there would be an outcry from women if anyone tried to introduce a prize for the best male novel, saying that she would actually welcome it.

The 20 contenders in the longlist for 2008 Orange Broadband Prize for Fiction include Enright, the Irish author, and the Scottish writer A. L. Kennedy, who was awarded the £30,000 Costa Book of the Year award for Day, a harrowing wartime novel.

Last year Kiran Desai became the youngest woman to win the Booker with The Inheritance of Loss, a story of an embittered retired judge in the Himalayas, while Stef Penney won the Costa for The Tenderness of Wolves a murder-mystery set in Canada.

This time seven debut novelists are up against established writers such as Deborah Moggach and Rose Tremain.

Also on the list is Linda Grant, whose victory in the 2000 prize was clouded by the discovery that passages of her novel bore a striking similarity to Mandate Days, a 1997 historical work by Joshua Sherman, who made a formal complaint to her publisher, Granta Books. Before the prize was announced, Granta agreed to include an acknowledgement to Dr Sherman in future editions. This time Grant has been longlisted for The Clothes on Their Back, a novel about identity and belonging.

The Orange has been controversial since its launch in 1996. Alain de Botton said at the time: “What is it about being a woman that is particularly under threat, in need of attention, or indeed distinctive from being a man when it comes to picking up a pen?”

Kirsty Lang, chairman of this year’s panel, denied yesterday that the Orange was positive discrimination, saying that most readers are women, and prizes are to attract readers.

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