Apple is on the verge of offering customers unlimited tracks from iTunes in return for an extra charge when they buy an iPhone or iPod.

The move is widely seen as a means of boosting sales and persuading consumers to ditch 'under the counter' methods of obtaining music via P2P sharing sites.

Apple executives believe that customers would be prepared to part with an extra $100 (around £50) for their iPod or iPhone at the point of purchase if it provided "all you can eat" access to Apple's iTunes library for the "lifetime of the device".

First reported yesterday in the Financial Times, Apple is also believed to be weighing up a second monthly subscription model for iPhone owners.

Users could pay an extra $8 on top of their monthly phone bill, in return for keeping "40 or 50" tracks per year even after their subscription has lapsed.

Apple is said to be in negotiations with leading record labels, although the company is reportedly offering just $20 per device.

The sum is $60 less than Nokia is believed to have agreed with the labels in December, when the firm announced its similar Comes with Music deal.