The research, which has been independently reviewed in accordance with ISO standards applicable to life-cycle assessments, looked at offset-only printing, digital-only printing and scenarios involving a mixture of both.

It found that combining analogue offset and digital inkjet printing can significantly reduce the number of copies returned by retailers without affecting the number of copies sold, and to lessen the environmental impact of printing, much of which, according to the report, comes from the resources used to create and transport paper.

The digital presses used in the study were the HP T200 and T300 web presses and an HP R85 Inkjet Press for in-store promotion.

Christopher Morgan, senior vice president, Graphics Solutions Business, HP, said that book publishers could boost profits by using digital printing to better match supply with demand.

He said: "Digital printing’s ability to efficiently and affordably produce books in smaller quantities reduces the masses of unused copy returns that have long held industry sustainability, and profitability, hostage."

Ralph Bell, chief operating officer of CPI Antony Rowe, the digital division of CPI UK, agreed.

"The study findings match our experiences," he said, "Publishers tend to order a more precise number of copies. They tend to order a low number and then come back for a reprint. Another benefit of digital printing is that you can print a whole book in one rather than having to print them in sections and have them put together, which will also help to reduce the carbon footprint".

CPI UK is investing £22m in digital print technology as part of a three-year programme and plans to buy 10 HP high-speed web presses.

The study results were presented at an event at Webcom Inc, the first publishing industry supplier in Canada to print books using an HP T300 Color Inkjet Web Press. The Toronto-based company also uses an HP Indigo 7000 Digital Press to produce covers for the books.