European Competition Commissioner Margrethe Vestager holds a news conference at the EU Commission's headquarters in Brussels, Belgium July 24, 2018. REUTERS/Francois Lenoir

LISBON (Reuters) - EU regulators are close to wrapping up their third case against Alphabet GOOGL.O unit Google involving its AdSense advertising service, Europe's antitrust chief said on Wednesday, suggesting the company may soon be hit with another hefty fine.

The comments by European Competition Commissioner Margrethe Vestager come four months after she levied a record 4.34 billion euro ($5 billion) fine against Google for using its popular Android mobile operating system to block rivals.

That followed a 2.4 billion euro fine imposed on the company last year after it thwarted rivals of shopping comparison websites.

The European Commission in 2016 opened a third case when it accused Google of preventing third parties using its AdSense product from displaying search advertisements from Google’s competitors.

“We are approaching the end of that investigation,” Vestager told reporters at the Web Summit in Lisbon when asked for an update on the investigation.

Google has denied the charges.

Vestager can fine companies up to 10 percent of their global turnover for breaching EU rules.

($1 = 0.8707 euros)