Boosting buyers

Google, for example, uses text recognition on its Gmail programme to offer adverts based on the contents of emails.

EBay's chief strategy officer, Michael van Swaaij, unveiled the plan at a conference of software developers in Las Vegas.

"We want to increase the number of times buyers come to particular sites," he said.

Examples cited of how the new system would work included a sports website that would carry links to eBay auctions for particular items of sporting equipment or memorabilia.

EBay is one of the biggest advertisers on both Google and Yahoo and the plan could reduce its reliance on these sites, analysts said.