Strong sales of grown-up fiction have boosted profits at publisher Bloomsbury, but the firm is still waiting for the next instalment of the best-selling Harry Potter children's series.

The company said pre-tax profits for the six months to June climbed to �3.1m ($4.3m), 9.8% up on the year, while sales rose 8% to �24.5m.

The publisher credited a strong performance from its reference and educational publishing subsidiary A&C Black, as well as brisk sales of new novels from authors Joanna Trollope and Sue Miller.

But the company was unable to give a launch date for the delayed fifth novel in the series.

"The publication date of the fifth Harry Potter novel will be announced after it has been delivered," the company said in a statement.

Vanishing act

The Harry Potter phenomenon was identified as the main factor behind a thumping 120% increase in Bloomsbury's profits for 2001.

Author J K Rowling has taken longer than expected to complete the fifth Potter book, forcing the firm to put back the original publication date.

Bloomsbury said it expected the second Harry Potter film, due to be released in November, to boost sales of its Potter back catalogue.

The company added that it is on track to publish the second novel from cult author Donna Tartt - whose best-selling first novel, The Secret History, came out ten years ago - in October.

Bloomsbury shares were unchanged at 612.5p in early trade.