The US Department of Justice is set to launch an inquiry into Apple's dominance of the music industry in the States.
Apple's market share amounts to 70 per cent of US sales.
The initial inquiry is based on a report presented by the NPD Group, a market research firm, to the regulators.
The antitrust regulators are hinting at a possible price-fixing issue between Apple and its closest competitor, Amazon.com.
The Department of Justice had earlier quizzed several high-ranking Apple officials regarding the report.
Apple and Amazon have had a well documented falling-out in the past, when Apple reacted badly to Amazon releasing its 'MP3 Daily Deals', which provided access to new tracks before launch.
An unnamed source from the DoJ told abcnews.com: "The conversation with Justice has nothing to do with Amazon getting (music) early. It has everything to do with whether iTunes is trying to control pricing."
According to the NPD report, Apple still rules the music industry with over 28 per cent of world-wide consumers choosing iTunes for music, followed by Amazon and Wal-Mart with 12 per cent market share each.