The US government is suing Google, seeking the breakup of its advertising business for alleged anti-competitive behaviour.

US Attorney General Merrick Garland said today that Google has abused its near monopoly in "Ad-Tech" - the automated buying and selling of advertising on websites and on mobile devices worldwide over the past 15 years.

The case against Google is the first antitrust case of the Biden administration, and follows a deep probe into Google's online advertising business.

In court filings the US Department of Justice said Google abuses its monopoly power to hurt online publishers and advertisers trying to use competing products.

It seeks a court order to unwind Google's 2008 purchase of ad-serving company DoubleClick, and the sell-off of the Google ad exchange.

The filing states: "Google uses its dominion over digital advertising technology to funnel more transactions to its own ad tech products where it extracts inflated fees to line its own pockets at the expense of the advertisers and publishers it purportedly serves".

Google said the lawsuit was an attempt by the government to pick winners and losers in the "highly competitive advertising technology sector".

Google’s business offering includes a tool for publishers to offer advertising space, a product for advertisers to buy available ad space, and an advertising exchange that automatically links ad space buyers and sellers as webpages are being loaded for individual users.