Pan Lloyds Publishers sales manager Sammi Leung said parents were spending more than HK$500 on average, with some spending almost HK$3,000 on exercise books and storybooks.

A Ms Chau, who did not give her full name, and her son Memphis Leung bought 60 books including storybooks, comics and academic texts for HK$2,500.

'Inflation is not affecting our spending plan because the books are discounted,' she said.

Commercial Press retail director Anita Wan Wai-ling said increased paper costs had caused prices to rise by around 4 per cent, but the group was offering discounts of up to 60 per cent on primary school textbooks and sets of books were being sold at a discount of more than 20 per cent to combat inflation.

'We hope there can be a 10 per cent increase in sales this year,' Ms Wan said. 'This year's sales are better than last year's.'

Longman Hong Kong Education and Oxford University Press were offering discounts of 15 to 50 per cent.

Oxford University Press marketing manager Debbie Lam said more parents were buying educational books for their children at the fair because of inflation, and she expected double-digit growth in fair sales this year.

Popular Book Company, Chung Hwa Book Company and Joint Publishing Company decided not to increase prices. Joint Publishing Company boss Anne Lee On said the cost of paper accounted for only a small percentage of the price.

While admitting that their profit margins were shrinking, the publishers said they preferred to maintain prices in the hope of better sales.

Popular Book Company general manager Iris Lok Hou-ming said yesterday's sales were better than on the opening day of last year's fair.

Chung Hwa Book Company senior manager Cherry Chen Chiu-ying said book titles related to China were selling well, with the total stock of 300 copies of Sichuan Earthquake sold by 7pm.

The Complete Collection of Treasures of the Palace Museum, produced by the Palace Museum and The Commercial Press (HK), was the most expensive publication among all the Chinese titles at the fair.

At HK$20,888, the 60-volume set covers the exhibits of the Palace Museum including costumes, drawings and furniture.

Hong Kong Olympics chief Timothy Fok Tsun-ting registered to buy the first set yesterday.

Other timely titles published included books on the use of slang in Hong Kong, a topic which caught the public's attention after students complained about the 'improper use' of slang in the Chinese listening paper of the Hong Kong Certificate of Education Examination earlier this year.

Slang expert Jimmy Pang Chi-ming said he had sold more than 300 of the 3,000 copies by noon, at a discounted price of HK$42.

This year's fair at the Convention and Exhibition Centre in Wan Chai has more than 480 exhibitors from 21 countries.