The European Commission may slap Alphabet's Google with a $9 billion fine for breaching EU antitrust rules, Reuters reported at the weekend.

The EU competition watchdog accused Google in April 2015 of distorting internet search results to favour its own shopping service at the expense of rival services in a case that has dragged on since late 2010.

Just over a year ago, people familiar with the matter told Reuters they believed that after three failed attempts at a compromise for the prior six years, Google had no plans to try to settle the allegations unless the commission changed its stance.

The search engine giant has been subject to an investigation by the commission since 2010 after complaints were received by Google's US and European rivals.

If found guilty of breaching antitrust rules, companies face fines of up to 10 percent of their annual sales turnover, which in Google's case would be a maximum possible sanction of more than €6 billion. The biggest antitrust fine to date was a €1.1 billion fine imposed on chip-maker Intel in 2009.

Apart from the fine, Reuters believes the commission will tell Google to stop its alleged anti-competitive practices but it is not clear what measures it will order the company to adopt to level out the playing field for competing companies.

Google agreed to pay €306 million in back taxes to Italy and Ireland last month, in a bid to end a criminal investigation into whether the company avoided paying the full amount on its revenues for more than a decade.

The agreement resolves multiple disputes including a criminal probe that saw Milan prosecutors accuse Google of generating revenues of €1 billion in Italy and Ireland between 2009 and 2013.

The sum also settles other disputes for the tax years 2002-2006 and 2014-2015.

The company worked out a similar deal with the UK a few years ago, paying £130 million to British tax authorities.

Google is currently facing another case in France where the authorities believe it owes €1.6 billion in back taxes. France's finance minister Michel Sapin said last year that he won't negotiate a deal with Google, but will instead pursue legal action.

Google is also in the midst of a court battle in Germany regarding the country's ancillary-copyright law, which gives press publishers the right to charge search engines such as Google for using snippets of articles in their news aggregators.