The row erupted after Amazon offered publishers who participate in its Advantage scheme an "early payment" option of 15 days in exchange for an extra 2% discount on top of the 60% already offered.

However, theBookseller.com reported that Advantage members were "more or less" paid to the new 15-day terms under the current system prior to these new terms.

It claimed publishers accused Amazon oftrying to "pinch" an extra month with the deal, which will see those who decline the offer paid to Amazon's standard terms of 60 days.

IPG executive director Bridget Shine said: "These changes will have an impact on the most cash flow-vulnerable publishers."

Following a meeting with the IPG last Friday (27 March), Amazon said that it would not be able to alter the terms, "especially for books".

Also see:
Amazon's latest e-book device gets mixed reaction from industry