Ottakar's, the bookshop chain, achieved a 19% increase in sales in the first half of the year boosted by the 24 stores it bought from Hammick's last year and the impact of a celebrity book club on the Richard and Judy show.

The firm recorded sales of £68m as the promotion of books by celebrities on the TV show lured new customers into the stores. It also benefited from a "4 for £10" offer on Penguin 21st century classic novels. The like-for-like sales growth for the period was 4%.

The company said it will open seven new stores by the end of the year, which will bring the total to 131. The new stores will be in towns such as Canterbury and Torquay, sticking to the firm's policy of opening in small towns.

The company also said that finance director, Edward Knighton, has resigned and will be leaving in November. Mr Knighton said it was "time for a change". "It's all entirely amicable, everyone accepts my reasons for going," he said.

The firm said that trading since the end of the financial year showed a like-for-like sales increase of 6.6%, indicating growth is accelerating.

The firm made a loss of £2.8m in the first half. The company makes most of its profits around Christmas. Investment bank Seymour Pierce predicts the firm will see a full-year profit of £9.1m this year.

Ottakar's said it is on track to meet market expectations for the year. It said that the books being published over Christmas were "strong". They include autobiographies by Graham Norton and rugby star Jonny Wilkinson, and new fiction from Maeve Binchy and Patricia Cornwell.

The company's debt grew by nearly £6m to £25m, near the limit of its facility of £26.5m. It will give shareholders a dividend of 2.4p per share.

The firm's share price fell by 11.5p to 363.5p.

"The results were perfectly in-line," said Rhys Williams, an analyst at Seymour Pierce. "Current trading is slightly better than anticipated. The schedule looks quite good for Christmas, and books are getting more and more popular anyway."

He added that competition in the book market was not too strong. "The supermarkets seem to be happy to go for the top markets, and one or two special deals, and WH Smith still seems to have no idea," he said.