The European Commission said Wednesday it had begun a preliminary investigation into Google's job search tool on competition grounds, having identified a conflict of interest.
"With respect to Google Jobs, our preliminary investigation is ongoing," a Commission spokesperson said, adding: "We cannot comment on or predict its timing or outcome.
On Tuesday, Competition Commissioner Margrethe Vestager said the issue needed addressing on competition grounds.
"There's an obvious conflict of interest here, an obvious temptation to adjust the way the platform works, to favour their own services ahead of others," Vestager said in Berlin.
"For instance, many platform businesses act as both player and referee - they run a platform, and also compete with other companies that rely on that platform.
"That's what Google did, when it used the power of its search engine to favour its own comparison shopping service. By doing that, it harmed competition and consumers - which is why we fined the company nearly two and a half billion euros, for breaking the competition rules.
"And we're looking right now at whether the same thing may have happened with other parts of Google's business - like the job search business known as Google for Jobs."
The Commission has the power to open a formal procedure if it finds sufficient evidence against Google, which could see the digital giant fined for a fourth time for what Brussels finds to be an excessively dominant market position.
The Californian behemoth's "Google Shopping" service was fined 2.42 billion euros ($2.7 billion) in July 2017, then 4.34 billion euros in July last year for antitrust violations with its Android operating system for smartphones. Last March it was fined 1.49 billion euros over search advert restrictions for third-party websites on its AdSense advertising service.
"What the Commission has found is that those different specialised services have some things in common - but they also have important differences," the Commission spokesperson said Wednesday.
"We need to look individually at each of those services," the spokesperson added, referring to a 2017 Commission decision to investigate search services.