Apple also said 2009 will be its last year exhibiting at the Macworld Expo, a multi-day gathering of fans and makers of software and accessories for Macs, iPods, iPhones and other Apple products.

The expo is organised by the IDG technology media group.

Mr Jobs' Macworld keynote had become one of the consumer electronics industry's most-awaited moments because he used the stage to launch Apple's most coveted gadgets. The chief executive, a practiced showman, is known for saving his biggest Macworld announcement for last, then prefacing the big revelation by telling his audience he has 'one more thing'.

Last year, that 'thing' was the ultra-thin MacBook Air laptop; in 2007, Jobs gave Macworld attendees the first glimpse of the iPhone. A decade earlier, as Apple was struggling financially and Mr Jobs had just returned as CEO, he wrapped up his keynote, paused, and then added: 'I almost forgot. We're profitable.'

Apple said Mr Philip Schiller, a marketing executive, will deliver the keynote instead of Mr Jobs. The switch indicates 'a shift in power going on at Apple', said Piper Jaffray analyst Gene Munster in an interview.

Mr Munster said Mr Schiller is one of two contenders to succeed Mr Jobs at the company's helm; the other is Chief Operating Officer Tim Cook.

Apple said it was abandoning Macworld because the company has other methods for getting in front of customers, including its growing chain of retail stores. Mr Munster said it makes sense for Apple to back out because it can generate just as much buzz by hosting its own product launch events.

But the analyst called that part of Apple's announcement insignificant compared with the news that Mr Jobs will not be delivering the keynote.

'This is his baby. This is his presentation. It's his flock,' the analyst said.

Mr Munster said he believes Mr Jobs' absence could mean that Apple doesn't have a big product to unveil this year, and that Mr Jobs refused to give a newsless talk.

Or, he said, it could mean Mr Jobs, who recovered in 2004 from a rare but treatable form of pancreatic cancer, is having health problems.

'I think that Apple could have done a lot to have made it so people wouldn't speculate about Steve Jobs' health,' he said.

Mr Jobs has appeared very thin but energetic at Apple events this fall. Apple spokesman Steve Dowling would not address questions from The Associated Press about Mr Jobs' health on Tuesday.

Apple shares dropped US$2.55, about 2.7 per cent, to US$92.88 (S$135.35) in after-hours trading, after gaining 68 cents to end the regular session at US$95.43. -- AP