The European Commission today opened two competition investigations against Google's Motorola Mobility.
This follows complaints from Apple and Microsoft in a patent war between the technology giants.
The EU competition watchdog said it would check whether Motorola had abused a dominant market position on patents.
It had sought court injunctions against Apple and Microsoft from selling their iPhone, iPad, Xbox and Windows products.
Microsoft and Apple accuse Motorola Mobility of unfairly using its patent portfolio to try to block competing products. In February, European Union and US regulators cleared the acquisition of Motorola Mobility for $12.5 billion (€9.4 billion) by Google.
At issue are what are known as standard essential patents (SEPs). SEPs are patents which have been identified by technology companies as necessary to allow them to build compatible products.
Motorola Mobility is failing to live up to an industry pledge to license SEPs to rivals on fair, reasonable and nondiscriminatory (FRAND) terms, according to Microsoft and Apple.
Motorola made FRAND commitments to standard setting organisations for 2G and 3G mobile and wireless telecommunications, H.264 video compression and WLAN technologies.
The commission said it would assess whether Motorola Mobility "has abusively, and in contravention of commitments it gave to standard setting organisations, used certain of its standard essential patents to distort competition in the Internal Market in breach of EU antitrust rules."
"The Commission will examine whether Motorola's behaviour amounts to an abuse of a dominant market position," it added.
The European Union's executive arm said it would also assess allegations by Apple and Microsoft that "Motorola offered unfair licensing conditions for its standard-essential patents in breach" of antitrust rules.
Brussels already opened in late January a similar case against South Korea's Samsung Electronics, which is embroiled in a multi-continent patent fight with Apple.
The European Commission is investigating whether the group went too far last year when it sought injunctions against mobile device competitors in various EU national courts, alleging infringements of Samsung's patent rights.
