Apple's unlimited downloads on iTunes service has been slammed by rivals as uncompetitive.

"I only know what I've read but the plan sounds very similar to the tying practices Microsoft used with Windows and Explorer," David Pakman, CEO of iTunes competitor eMusic, told Cnet. "And Microsoft is still paying the penalties for that one."

Earlier this week the Financial Times reported that Apple was considering offering an unlimited downloads deal to iPod and iPhone owners.

See: iPhone/iPod to get unlimited iTunes downloads.

According to Pakman, Apple's dominance of the MP3 player market would mean that other music services, such as his, would essentially be walled off from 70 percent of the market, as customers wouldn't need to look anywhere else to purchase their music.