RIYADH: The Ministry of Culture and Information's Cultural Affairs Department has warned publishers against distributing books, leaflets, tapes and any other cultural material at next year's Riyadh Book Fair without receiving official, written approval at least two weeks before the opening of the event. The ministry said it will not allow the sale of unapproved books, and that it has required publishing houses that wish to take part in the book fair to offer at least a 20 percent discount to visitors. It added that book prices must be endorsed by the appropriate authorities in the country in which the publishing house is registered. The book fair, scheduled to open on March 31, 2011 with India as the guest of honor, has allocated a website for publishing houses that wish to participate in the event.