Google has launched an ad-blocker for its Chrome web browser that is designed to prevent "annoying" and "intrusive" ads being shown to users. Google announced the move to curtail full-page and auto-playing video ads, among others, last year.

The choice of which ads to block will be determined by the Coalition for Better Ads (CBA) - made up of companies including Google and Facebook.

Sites will have 30 days to remove disruptive ads before blocking begins. A survey of 40,000 US and European web users found that the most intrusive ads were full-page ads that hide the content of a web page and flashing animated ads, according to a blog by Chris Bentzel at Google.

"Chrome will automatically block ads on sites that fail the Better Ads Standards," wrote Bentzel. "When at least one network request has been blocked, Chrome will show the user a message indicating that ad blocking has occurred as well as an option to disable this setting....."

The ad industry was generally accepting of the move, said Emily Tan, an editor at Campaign magazine. "At first, people were worried that it would be implementing ad-blocking across the board," she told press.

Sites that have already altered the ads they show after being warned by Google include the LA Times and the Chicago Tribune.

However, users who simply want to block as many ads as possible may seek other solutions. Rival firm Adblock Plus has analysed how effective a CBA ad-detection tool can be, in terms of its ability to block ads described in a CBA white paper published last year.

The analysis found that the CBA blocker failed to prevent ads that re-positioned article text on a web page while users were reading it, for example to make way for auto-playing video ads.

"In total, the new CBA-endorsed ad skimmer will only block 16.4 percent of the ad types listed in its white paper " said a spokeswoman for Adblock Plus.

She added that Adblock Plus blocks 92.7% of ads by comparison. The Chrome browser is in use on approximately 60% of computers and mobile devices, according to statistics from Stat Counter, W3Counter and Net Applications.