The website of the Borders bookshop chain in the UK has stopped taking new orders for books while "the business is in discussion with potential buyers".
The firm says that existing customer orders are also being delayed but will be fulfilled.
The Borders Entertainment part of the site - which sells DVDs, CDs and electrical items - continues to operate as normal.
Some publishers are also reported to have severed links with the retailer.
When customers try to order a book on the website they receive a message saying: "Sorry, title cannot be purchased".
Reports have suggested Borders does not have enough cash to last until Christmas. It is thought it could go into administration if no buyer is found.
Talks with WH Smith reportedly collapsed last week.
The chain, which also owns Books Etc, has suffered from increased competition from online retailers, such as Amazon, as well as supermarkets.
Borders was originally owned by the US book giant of the same name but was sold in June 2007 to Risk Capital Partners.
Risk Capital then sold it on to the private equity firm Valco earlier this year.