Apple is once again protecting its trademark turf, this time with a suit against Amazon that takes aim at the Web retail giant's use of the term "App Store."

The suit, which was filed last week and first reported by Bloomberg this afternoon, goes after Amazon's use of the "App Store" name, which Apple filed a trademark for following the release of the iPhone 3G.

The suit seeks to prevent Amazon from using the phrase on its site or in marketing materials, according to Bloomberg. Apple is also seeking damages.

Amazon spokesperson Mary Osako said the company had no comment. In a phone call with CNET, Apple spokesperson Kristin Huguet said that the move was to keep people from getting confused.

"We've asked Amazon not to copy the app store name, because it will confuse and mislead customers," Huguet said.

Amazon first announced plans to enter the world of mobile-application publishing in September, unveiling a $99 developer program and an upcoming storefront called the "Appstore" that will sell Android applications outside of Google's own Marketplace application. As part of that process, Amazon gets either 70 percent of the sale price, or 20 percent of the list price (depending on what's higher).

Besides Android, Amazon has hinted that it plans to expand into other operating systems, though that list is likely to not include Apple's iOS given the vertical nature both of the storefront, and the installation mechanism through iTunes on the desktop, as well as the App Store application on the mobile side.

While Apple plays offense on Amazon, it's been playing defense against Microsoft over the same trademark. In January, Microsoft filed a motion against the trademark application, saying that it was too generic. Apple's response to that was then put to question by Microsoft earlier this month for trying to get around the font size, and length limits for legal briefs.