Small bookshops, and even the industry itself, could be devastated by the 'predatory pricing policies', warns the American Booksellers Association Photograph: Martin Godwin/Guardian

Independent bookshops in the US have urged the justice department to investigate a "predatory" online price war between huge retailers such as Wal-Mart, Amazon and Target that has cut the price of hard-back bestsellers to $9 (£5.50).

Works by popular authors including John Grisham, Stephen King and Barbara Kingsolver, typically selling for $25 to $35, have been the subject of deep discounts by powerful US players this month in a battle for online supremacy in book sales.

The American Booksellers Association, a 109-year-old trade body representing locally owned shops, says the consequences will be "catastrophic" if the price cuts continue, with small stores at risk of closure and creativity left in jeopardy.

"If left unchecked, these predatory pricing policies will devastate not only the book industry, but our collective ability to maintain a society where the widest range of ideas are always made available to the public," the ABA warned regulators.

The price war broke out a week ago, when the largest US retailer, Wal-Mart, cut some pre-order prices to $10. The titles include a memoir from the former vice-presidential candidate Sarah Palin and a volume of short stories by Grisham.

Amazon and Target matched these prices and the three have slugged it out, cent by cent: Amazon went down to $9 in the US, Target cut titles to $8.99 and Wal-Mart went one better, down to $8.98. In Britain, discounting has been less extreme, although Amazon is offering advance orders of Grisham's book at £10.44, compared with a recommended retail price of £18.99.

Local bookshops in the US say the big retailers are selling far below cost, losing up to $8.50 on each book, in an effort to lure customers to their websites to buy more profitable products such as clothes, jewellery and household appliances.

"They're using our most important products, mega-bestsellers – which, ironically, are the most expensive books for publishers to bring to market – as a loss leader to attract customers to buy other, more profitable merchandise. The entire book industry is in danger of becoming collateral damage in this war," the ABA says.

Among those alarmed about discounting is Grisham's agent, David Gernert, who told the New York Times: "If readers come to believe that the value of a new book is $10, publishing as we know it is over."

The environment has been tough for bookshops for some time. One big chain, Borders, flirted with bankruptcy in the US this year, and there is concern in the trade at the low price at which digital version of books are being sold on electronic devices such as Amazon's Kindle.

Wal-Mart and its rivals have shrugged off the criticism, arguing that they are simply offering attractive prices to customers during a period of economic hardship. "We are commited to providing our customers with low prices, and our online book announcement demonstrates that commitment," said a Wal-Mart spokeswoman. "We always comply with applicable law."