Google is set to build its own ad blocker and add it to the Chrome web browser, according to a new report.

The technology giant is expected to switch it on by default on mobile and desktop.

Since Google makes most of its revenue from advertising, this seems like a highly unusual move that could seriously impact its earnings.

However, there’s legitimate concern that that company will take great care to protect its own interests.

According to the Wall Street Journal, Google’s ad blocker will only target adverts that the Coalition for Better Ads considers to be “unacceptable”.

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The industry group, which was founded last year, counts Google as one of its members.

“Testing of consumers for desktop web and mobile web reveals that consumers clearly differentiate between different types of ad experiences, producing overall rankings that identify the most and least preferred ad formats,” reads a report on the Coalition for Better Ads website.

“Annoyance and distraction were among the most important factors in determining whether an ad experience would fall beneath the threshold defined by a Better Ads Standard.”

For mobile users, the Coalition for Better Ads says pop-up ads, prestitial ads (those that block the content you actually want to access by loading first), pages with more than 30 per cent ad density, flashing animations, poststitial ads that require a countdown to dismiss, full-screen rollover ads, large sticky ads and auto-playing videos with sound are “least preferred”.

On desktop, the “least preferred” list includes cut to pop-up ads, auto-playing videos with sound, prestitial ads with a countdown and large sticky ads.

Though Chrome is the world’s most popular browser, many web users prefer rival browsers, such as Edge, Safari and Firefox.

Google is well aware of this, and the report says the company could exercise its power by blocking all ads on sites that use a mix of “acceptable” and “unacceptable” ads, in the hope that those that don’t get past Chrome’s ad blocker are seen by users on other browsers.