Microsoft has filed a formal complaint against Google with the European Commission (EC), accusing its rival of anti-competitive behaviour.
It marks the first time Microsoft has filed an antitrust complaint with the EC and comes as Google is being investigated by the same body over whether it broke European competition law.
Google has faced a number of investigations into its competitive actions in the US, where it has less of a market share than in Europe.
In its EC filing, the Redmond giant claimed Google was guilty of engaging “in a broadening pattern of walling off access to content and data” which rivals needed to compete in the market and attract advertisers.
Microsoft gave a number of examples where it believed Google had impeded competition, including the 2006 acquisition of YouTube.
According to Microsoft, Google implemented “a growing number of technical measures” to prevent other search engines from including YouTube videos in results.
Google was also accused of blocking Windows Phone 7 devices from using YouTube properly, preventing access to extra services, such as the ability to find favourites and see ratings.
“Microsoft is ready to release a high quality YouTube app for Windows Phone,” said Brad Smith, vice president and general counsel for Microsoft, on a blog.
“We just need permission to access YouTube in the way that other phones already do, permission Google has refused to provide.”
Microsoft claimed Google also sought to prevent others from offering so-called “orphan books” – those publications without a copyright holder.
The Redmond firm then moved on to advertisers, alleging Google “contractually prohibits advertisers from using their data in an interoperable way with other search advertising platforms, such as Microsoft’s adCentre.”
“This makes it much more costly for Google’s advertisers to run portions of their campaigns with any competitor, and thus less likely that they will do so,” Smith said.
“That is a significant problem because most advertisers figure that they have to advertise first with Google.”
Microsoft also suggested Google had got its claws into search boxes within websites by contractually blocking “leading websites in Europe from distributing competing search boxes.”
“Finally, we share the concerns expressed by many others that Google discriminates against would-be competitors by making it more costly for them to attain prominent placement for their advertisements.”
“Microsoft has provided the Commission with a considerable body of expert analysis concerning how search engine algorithms work and the competitive significance of promoting or demoting various advertisements.”
In a statement, a Google spokesperson said the firm was not surprised Microsoft had taken the step as a subsidiary - Ciao.de - was one of the original complainants which sparked the EU investigation.
"For our part, we continue to discuss the case with the European Commission and we're happy to explain to anyone how our business works," the spokesperson added.
The search spat between Microsoft and Google stepped up a notch earlier this year, when the Redmond giant was accused of copying Google results.
Google claimed it saw various URLs from its own search results appear in Bing “with increasing frequency for all kinds of queries.”
Microsoft denied the claims, saying it used “multiple signals and approaches in ranking search results.”