NEW YORK: Targeted eBook ads based on reader demographics are to be trialled by marketers in a bid to capitalise on strong US sales.

Forrester Research predicts that, with big names such as Apple, Amazon and Google pushing digital readers, sales of traditional books could come under increased pressure.

According to the research firm, 7% of all US adults who go online now read electronic books and it expects that figure to double by next year.

More generally, eBook sales are predicted to grow from $1 billion (€0.75bn; £0.63bn) this year to more than $2.8 billion (€2.1bn; £1.7bn) by 2015.

People with eBook readers consume up to 40% of their book choices in electronic form, with laptops and Kindles accounting for 35% and 32% of delivery respectively.

Despite scepticism from print publishers, firms are already exploring a variety of advertising formats including videos, graphics or text that appear when a reader opens a book, as well as sponsorship link-ups that provide consumers with free titles.

The Los Angeles-based digital bookstore Wowio is currently trialling eBooks incorporated three pages of promotions per title; an introductory and closing page, together with a third full-page ad space.

The retailer is also experimenting with inserting ads between specific chapters and using profile information submitted to its website by users to target ads more effectively.

"It is not the kind of thing where you are reading and a video pops up on the screen," Wowio chief executive Brian Altounian said.

"If advertising gives access to content that is free or heavily subsidized, then most readers will accept it."

But there are many problems to be overcome by the pioneers of eBook ads.

With most books selling only a few hundred thousand copies, potential reach remains an issue, as is the question of ensuring that ads remain fresh over a book's prolonged lifespan.

Author permission will usually need to be granted for an ad to be inserted and reader annoyance is also likely to prove a major factor.

Stuart Applebaum, a spokesman for Bertelsmann AG's Random House, said that while ads routinely appeared in the back of mass-market paperbacks in the 1950's and early 1960's, they failed to become a significant revenue source.

The practice was eventually abandoned, due in part to author objections.

Inserting ads in Random House eBooks won't happen today without the express approval of authors, Applebaum said.

"It's a non-starter here without their assent, regardless of format," he added. "However, if our authors were ever to be agreeable to it, it might have some traction."

Data sourced from Wall Street Journal; additional content by Warc staff