Google has been fined 1.49 billion euros ($A2.38 billion) for blocking rival online search advertisers, the third large European Union antitrust penalty for the Alphabet-owned business in just two years.

The EU antitrust chief, however, has given a cautious welcome to Google’s measures to boost competition and give Android users a choice of browsers and search apps, suggesting the company’s regulatory woes may be coming to an end.

The European Commission said the fine amounted to 1.29 per cent of Google’s turnover in 2018 and that the case focused on the company’s illegal practices in search advertising brokering from 2006 to 2016.

“Today’s decision is about how Google abused its dominance to stop websites using brokers other than the AdSense platform,” European Competition Commissioner Margrethe Vestager said.

She said the company’s actions meant advertisers and website owners had less choice and likely faced higher prices that would then be passed on to consumers.

The case concerned websites, such as newspaper or travel sites, with a search function that produces search results and advertisements. Google’s AdSense for Search provided such search adverts.

The misconduct included stopping publishers from placing any search advertisements from competitors on their search results pages, forcing them to reserve the most profitable space on these pages for Google’s adverts and a requirement to seek written approval from Google before making changes to how rival adverts were displayed.

Google senior vice-president of global affairs Kent Walker said the company would make further changes to its products to address the EU antitrust concerns.

“We’ve always agreed that healthy, thriving markets are in everyone’s interest,” Mr Walker said.

We’ve already made a wide range of changes to our products to address the Commission’s concerns.

“Over the next few months, we’ll be making further updates to give more visibility to rivals in Europe.”

Ms Vestager welcomed the move, saying: “We see positive developments both in the shopping and Android case.”

Last year, Ms Vestager fined Google a record 4.34 billion euro ($A6.9 billion) for using its popular Android mobile operating system to block rivals.

This followed a 2.42 billion euro ($A3.86 billion) fine in June 2017 for hindering rivals of shopping comparison websites.

Google’s foe, the Initiative for a Competitive Online Marketplace, said regulators should stay vigilant.

“Competitors have withered or died. It’s time for the EU and governments around the world to step in and address the underlying wrong,” its chairman Michael Weber said.

-AAP