Google has announced beta trials of "interest-based" advertising in a move that it says will make "ads more interesting" to web users.

As most netizens will know, Google already displays adverts based on what users look at or search for. So if you search for "digital cameras" on Google, the ads that come up will be related to that topic.

These new plans take that a step further though - by assessing the user's web history as well as the current activity. It's likely to prove unpopular with privacy campaigners who believe Google already holds too much info on its users.

In a blog post, Susan Wojcicki, VP of product management, explains the new scheme:

"We are launching 'interest-based' advertising as a beta test on our partner sites and on YouTube. These ads will associate categories of interest - say sports, gardening, cars, pets - with your browser, based on the types of sites you visit and the pages you view. We may then use those interest categories to show you more relevant text and display ads".

In addition, users will be able to "tell" Google what kind of ads they do and don't want to see via a tool called "Ads Preferences Manager". Again from Wojcicki:

"You can also choose your favourite categories, or tell us which categories you don't want to see ads for. Interest-based advertising also helps advertisers tailor ads for you based on your previous interactions with them, such as visits to their websites. So if you visit an online sports store, you may later be shown ads on other websites offering you a discount on running shoes during that store's upcoming sale".

Google acknowledges the privacy issues and will offer the option to opt out through a plug-in for browsers that maintains a user's opt-out choice, even if cookies are deleted.