Kaspersky Lab has filed an antitrust complaint against Microsoft over allegations that Redmond is hobbling third-party antivirus software.

The complaint was submitted to both the European Commission and German Federal Cartel Office this week following an investigation begun by Russia's Federal Antimonopoly Service in November last year.

Kasperky Lab claims that Microsoft is abusing its "dominant position in the computer operating system (OS) market to fiercely promote its own – inferior – security software (Windows Defender)" at the expense of any third-party security software users have chosen to install. This applies to Kasperky Lab's rivals as much as it does to the Russian software maker, it is alleged.

"[This] promotion is conducted using questionable methods, and we want to bring these methods to the attention of the anti-competition authorities," said CEO Eugene Kaspersky.

According to Kaspersky, Microsoft has resolved some of the issues in contention but not enough, hence the appeal to European competition authorities. Among the features in contention are the pop-up dialogue boxes Windows 10 generates when a user tries to run third-party antivirus software, the disappearance of security software when Windows 10 is upgraded and advice by a support worker that "Windows 10 is incompatible with third-party antivirus" among other factors explained in more detail here.

This is bad for users because Windows Defender underperforms in independent antivirus tests run by the likes of AV-Test and others, the argument goes.

"We want Microsoft to stop misleading and misinforming our – and not only our – users," Kaspersky concludes. "We want to see all security solutions being able to work on the Windows platform on a level playing field. And we want to see users being able to decide for themselves what they want and consider important to them."

In a statement, Microsoft expressed confidence that it can persuade competition watchdogs that it had done nothing wrong.

Microsoft's primary objective is to keep customers protected and we are confident that the security features of Windows 10 comply with competition laws. We're always interested in feedback from other companies and we engage deeply with anti-malware vendors and have taken a number of steps to address their feedback. We reached out directly to Kaspersky a number of months ago offering to meet directly at an executive level to better understand their concerns, but that meeting has not yet taken place.

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