Google has accused Microsoft of hypocrisy in response to the firm filing a complaint with the European Commission (EC) over concerns Motorola is abusing its industry standard patents to threaten competitors' products.
A Google spokesperson said the firm had not seen the document itself, but said it found the firm's stance hypocritical given its supposed history in using legal arguments to attack other companies.
"We haven't seen Microsoft's complaint, but it's consistent with the way they use the regulatory process to attack competitors," it said.
"It's particularly ironic, given their track record in this area and collaboration with patent trolls."
Microsoft had earlier outlined its numerous concerns with Motorola's tactics, which is being bought by Google, and it comes just two days after Apple filed a similar request with the EC.
The statement from Google underlines the increasingly poor relations between the two firms.
They have clashed over several issues in recent months including smartphone patents, with Microsoft accused of extortion by Google for signing licensing deals with Android vendors that cover 70 per cent of all devices sold.
The two firms have also clashed over privacy issues, with Microsoft using adverts in national newspapers in the US to try and tempt Google customers to its own services when concerns were raised over the search giant's announcement it would amend its privacy policies.
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