It seems like a small issue: Microsoft, unable to create what it calls a “first-class” YouTube experience on Windows Phone, is complaining yet again that Google is blocking it from doing so. But Microsoft claims that Google’s behavior is anti-competitive and represents a rebuff of US antitrust laws, and is thus a far bigger concern.

In a post to the Microsoft on the Issues blog on Wednesday, Microsoft deputy general counsel Dave Heiner once again raised an issue the firm first complained about in late 2010—that Google is explicitly and purposefully blocking it from creating a full-featured YouTube app for Windows Phone. And that by doing so, Google is not conforming to antitrust laws in the United States and Europe.

“You might think that Google would be on its best behavior given it’s under the bright lights of regulatory scrutiny on two continents, particularly as it seeks to assure antitrust enforcers in the US and Europe that it can be trusted on the basis of non-binding assurances that it will not abuse its market position further,” Mr. Heiner writes. “However, as we enter 2013, that is not the case.”

According to Heiner, Microsoft first complained in 2010 that Google was “blocking” its YouTube video service from working properly with Windows Phone handsets. “Google has enabled its own Android phones to access YouTube so that users can search for video categories, find favorites, see ratings, and so forth in the rich user interfaces offered by those phones,” Heiner explained. “It’s done the same thing for the iPhones offered by Apple, which doesn’t offer a competing search service.”

But Google does not allow Windows Phone to access this YouTube metadata in the same way that Android and iPhone handsets do. “Microsoft is ready to release a high-quality YouTube app for Windows Phone,” he claims. “We just need permission to access YouTube in the way that other phones already do, permission Google has refused to provide.”

Heiner says that Microsoft has engaged YouTube personnel for over two years about the issue that it, too, would like all of its customers—including those using Windows Phone—to have a great YouTube experience. “But just last month we learned from YouTube that senior executives at Google told them not to enable a first-class YouTube experience on Windows Phones,” Heiner writes. “Google’s refusal deprives consumers who use competing platforms of a comparable experience in accessing content that is generally available on the Web, almost all of which is created by users rather than by Google itself.”

This issue is much broader than just the relatively small number of people who use Windows Phone handsets, Heiner notes. While this is happening, Google is under government scrutiny around the globe for various antitrust infractions. And as Heiner notes, Google has said that the antitrust offenses with which it has been charged cause no harm to consumers. “Google is wrong about that,” Heiner asserts. “Consumers and competitors alike are getting ‘scroogled’ across the Web on a daily basis from this type of misconduct.”

Heiner hopes that by going public with this information, he can convince Google to do the right thing and conform to antitrust laws. If not, he would like to see “antitrust enforcers display the resolve that Google continues to lack.” (See also "What You Need to Know About Google Apps.")