The Federal Trade Commission and the U.S. Department of Justice are looking into the prospect of launching an antitrust inquiry against Apple (news, site) following the company’s ban of developers using non-Apple-sanctioned development tools, according to a story in the New York Post. Filing an inquiry doesn’t necessarily mean that charges would follow, the NYP reports.

Apparently, the two agencies are deciding which one would start an investigation. Both federal entities and Apple have declined to comment.

New SDK Rules for OS4 Upsets Devs

At issue are the new terms of service agreement for iPhone OS4 -- set to debut in June -- which limits the tools developers can use to create their apps. Apple has banned compilers that do not expressly rely on C, C++ or Objective-C calls to Apple’s APIs as well as any private, third-party APIs. The move is being viewed as a way to stymie competition from Google, Adobe and others.

“This latest Developer Agreement shuts out Flash, as well as Titanium, Unity3D, Ansca, MonoTouch, RevMobile and others,” says Chipp Walters, a software programmer, in his blog. “Can you imagine working so hard for months and man-years on an iPhone development platform to have Apple yank it because they can, and because Steve Jobs has a vendetta against Adobe?”

Apple, for its part, says it’s doing what it has done all along: Maintain a closed system to ensure the quality of mobile apps designed to run on its devices.

The problem is not the rules, said David Bernard, developer of Gas Cubby and other apps for the iPhone and iPod touch. “I  like the walled garden approach! It's the ambiguity and shifting of the walls that bugs me.”

One Million iPads Outpace iPhones

The speculation regarding a potential antitrust action against Apple follows a fast start for the iPad. Apple announced that it sold its one millionth iPad, just 28 days after its introduction on April 3. iPad users have already downloaded more than 12 million apps from the App Store and more than 1.5 million ebooks from the new iBookstore, Apple said

"One million iPads in 28 days—that's less than half of the 74 days it took to achieve this milestone with iPhone," said Steve Jobs, Apple's CEO. "Demand continues to exceed supply and we're working hard to get this magical product into the hands of even more customers."

Developers have created more 5,000 new apps for iPad that take advantage of its Multi-Touch user interface, large screen and high-quality graphics, the company said in a prepared statement.

According to other news sources, the FTC is also looking into whether Apple and Google’s each having the same two directors on its boards violates antitrust laws. Google Chief Executive Eric Schmidt and Arthur Levinson, the former chief executive of Genentech Inc., sit on the boards of both companies. The government has the right to intervene under antitrust laws if it believes having overlapping directors could reduce competition.

As expected, spokesmen for Google and Apple have declined to comment.