By Katie Marsal

Published: 09:45 AM EST (06:45 AM PST)

Regulators from the European Union have reportedly joined the U.S. Federal Trade Commission in investigating Apple and its practice of blocking Adobe Flash from iOS devices, including the iPhone and iPad.

On Tuesday, the New York Post cited a source in reporting that European Commission has joined the FTC in an alleged ongoing investigation into Apple's anti-Flash stance. The report claims that the FTC began its investigation in June, and the European Commission recently joined the probe "into whether Apple's business practices harm competition."

The sources said the investigation could last another four to six months, though both the European Commission and FTC declined to comment, or officially acknowledged the ongoing investigation.

Last week, indications of the FTC's investigation surfaced when the commission denied a Freedom of Information Act request for documents related to a complaint filed by Adobe against Apple. The FTC said that the release of the information would impede its "law enforcement" duties.

The FTC will never publicly confirm its investigations, except when it decides to sue or reaches a settlement with a company. But the commission's decision not to release 189 pages related to Adobe's complaint against Apple strongly suggest that such an investigation is ongoing.

If true, the information from the Post's source would not only confirm the investigation, but also indicate that it is expanding overseas. The report noted that the EU recently adopted a new "Digital Agenda," which encourages interoperability of services between devices.

Adobe filed its complaint with the FTC after Apple announced it would not allow iOS applications ported from other languages or development environments, such as Flash. Adobe had created an application that would allow developers to port software written to Flash to the iPhone circumventing Apple's ban of Adobe Flash from iOS devices, including the iPhone and iPad.

But Apple changed its developer agreement, banning applications written in non-native languages and ported to the iPhone. That prompted Adobe to abandon development of its Flash-to-iPhone porting software, and file a complaint with the FTC.

Apple's stance on Flash for mobile devices was made clear in an open letter from Chief Executive Steve Jobs, published in late April. Jobs slammed Adobe Flash as a Web tool that is unfit for the modern, mobile era of computing. He also said that an intermediary tool for converting Flash applications to the iPhone would produce "sub-standard apps," and would hinder the progress of the platform.