Apple has unveiled upgrades to each of its existing iPod media players.

The iPod Shuffle, Nano and new 'Classic' lines will all receive cosmetic and performance upgrades in the hope of boosting sales over the holiday shopping season, chief executive Steve Jobs said at a company event in San Francisco.

The most noticeable of the upgrades was bestowed on the iPod Nano. The Flash-based player, which is the top seller in the iPod line-up, has been given a shorter, fatter design that essentially makes it a scaled down model of the original iPod.

The new design will allow the Nano to accommodate a 2in screen capable of displaying video at the same 320 x 240 resolution as the video iPod models.

The hard drive-based Classic, previously known simply as the iPod, will feature an all-metal casing and will be available in 80GB and 160GB capacities.

The new name allows Apple to distinguish the traditional iPod from the newly launched iPod Touch, which is essentially a 8GB or 16GB iPhone without a cellular function. Similar to the iPhone, it also offers a Wi-Fi connection and mobile browser.

Both the Nano and Classic players will be given a new navigation interface which displays photo, movie or cover art images alongside the menu. Users will also be able to browse music in both players via Apple's Cover Flow.

The clip-on iPod Shuffle has been given a new paint job, including a Product Red model for which a portion of the proceeds go towards Aids research.

All three of the renewed iPod lines are expected to hit the shelves by the end of this week.

Apple has also released a new version of iTunes to accommodate the new players. The update will include a new feature which allows users to create iPhone ring-tones as 30-second fragments from music files.

The custom tones will cost users 99c each, in addition to the purchase price of the song from the iTunes store. Not all iTunes songs are available as ring-tones, although the media store offers a selection of 500,000 songs.