The publisher, unveiling a 6.9 per cent rise in pre-tax earnings for 2004, said that growth this year would be underpinned by the release of Harry Potter and the Half-Blood Prince in July.

Pre-orders for the title had been "substantially higher than originally anticipated", Nigel Newton, the Bloomsbury chairman, said.

With new books also due from John Irving, the author of The World According to Garp and The Cider House Rules, and Ben Schott, the author of Schott's Original Miscellany, Bloomsbury said that underlying pre-tax profits would reach at least £20 million this year.

"Bloomsbury will show significant progress in 2005," Mr Newton said.

Last year, pre-tax profits hit £16.4 million despite a 22.7 per cent plunge in takings from children’s books, which accounted for half group turnover. The decline was blamed on the lack of a fresh Harry Potter title.

Sales of adult books surged by 64.2 per cent to £30.1 million, driven by Schott's Original Miscellany and Susanna Clarke’s Jonathan Strange & Mr Norrell.

Growth was also underpinned by expansion into America and Germany. Bloomsbury last year for first time boasted a book at the top of bestseller lists in the UK, Germany and the US.

The data was welcomed by analysts, and prompted Dresdner Kleinwort Wasserstein to place a "buy" rating on Bloomsbury shares. "US and German operations have made good operational progress through the year which augers well, while the UK performance remains robust, both on revenues and margins," the broker said.

At Investec, Malcolm Morgan said: "Given that the guidance is some 10 per cent higher than we were expecting, I would have thought investors would be more than gently pleased this morning."

Numis, raising its recommendation on Bloomsbury stock to "buy" from "hold", said: "We believe Bloomsbury will have another excellent year, driven by the new Harry Potter book but complemented by growth elsewhere in the portfolio.

"We would not be surprised if there were further upgrades as the year progresses."

Bloomsbury shares stood 10p higher at 316p in afternoon trade.

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