Apple's iPod music player continues to help the company grow revenue at dizzying rates, leading Apple to its highest fourth-quarter revenue in nine years, the company said yesterday.

Revenue for the period ending September 25 was $2.35 billion (around £1.32 billion), up 37 per cent from the $1.72 billion in revenue recorded during last year's fourth quarter.

Apple increased Macintosh shipments by 6 per cent and iPod shipments by an amazing 500 per cent compared to the fourth quarter of last year, the company said. A total of about two million iPods were shipped during the quarter.

Net income for the quarter was $106 million, up from the $44 million in net income posted during last year's fourth quarter.

Apple's music business is quickly becoming one of its crown jewels. For the first time, the company earned more revenue from the iPod during the quarter than from any other product. Total revenue from iPod shipments was $537 million with revenue from PowerBook sales trailing at $419 million.

The increase in iPod shipments was driven by the introduction of the iPod Mini in Europe and the rollout of the fourth generation of the product, said Peter Oppenheimer, Apple's chief financial officer.

Apple enjoys a leading position in the markets for both music players and online music downloads, according to market research released this week. The company plans to add more features over the upcoming year to build on that position, Oppenheimer said.

Like other PC companies, Apple has struggled with some inventory problems this year. However, Apple is trying to keep up with demand for its products while other PC companies that use processors from Intel have to deal with excess inventory.

Shipments of both iMac and Power Mac systems fell in the fourth quarter compared to last year, as processor supply problems continued to affect Apple's shipments, Oppenheimer said. Increased shipments of Apple notebooks accounted for the overall growth in shipments of Macintosh systems.

IBM supplies the processors for Apple's Power Mac G5 and iMac G5 systems. The supply of those processors has remained constrained throughout the fourth quarter, although the situation improved toward the end of the quarter, said Tim Cook, executive vice president for worldwide sales and operations at Apple.

One of the other reasons behind Apple's resurgence is the growth of its retail store network, Oppenheimer said. Revenue from Apple's retail stores increased 95 per cent compared to last year. Apple will soon open its first European store in London and plans to expand its retail operations in both Europe and Asia over the coming fiscal year.

For the 2004 fiscal year, Apple recorded revenue of $8.28 billion and net income of $276 million, both substantial increases over the company's results in 2003. Apple expects revenue to grow to between $2.8 billion and $2.9 billion during the consumer-focused first quarter of its fiscal year.