Google has begun testing a new pay-per-click (PPC) ad format designed specifically for products.

These product ads are being trialled on a limited basis in the US only and are displayed as sponsored links when web users search for particular items on Google.

The ads contain product-specific information such as pictures and prices and have been designed to complement the existing text-only PPC ads in use for website promotion purposes at the moment, Google stated.

According to the Google Blogoscoped blog, an email sent by the search engine to invited advertisers said: "This opportunity is a very tangible benefit of the integration of our affiliate platform into Google.

"Google is constantly experimenting with new features and visuals to improve ad effectiveness and advance the end user experience."

The information contained within the new ads is taken from the advertiser's Google Base feed. Advertisers are unable to add keywords to their ads as a result, Google said.

Google's financial results for the first quarter of 2009 revealed that aggregate paid clicks for Google sites and AdSense partners rose by 17 per cent compared with the same period in the previous year.