A glitch on Apple's iPhone has stopped its built-in alarm clock going off, leaving many people oversleeping on the first two days of the New Year.

Angry bloggers and tweeters complained that they had been late for work, and were risking missing planes and trains.

Apple has acknowledged the problem and says it will be fixed by 3 January.

The reason has not been given but the glitch appears to affect single alarm settings on the iPhone 4 and earlier models with software updates.

According to the company, the problem will resolve itself on 3 January, but that is two days late for many people”

A similar problem hit the iPhone alarm when the clocks went back in November, again causing many users to be late for work or for transport arrangements.

"We're aware of an issue related to non-repeating alarms set for January 1 or 2," Apple spokeswoman Natalie Harrison said in a statement quoted by Macworld.

"Customers can set recurring alarms for those dates and all alarms will work properly beginning January 3."

'Two days too late'

The problem is embarrassing for Apple, not only because of previous problems that came to light when the clocks changed, but because the company prides itself on the simplicity of use of its products.

This seems like another simple error, but it cannot afford to have too many before its reputation becomes tarnished, he says.

Apple failed to patch the problem last time - meaning the same alarm bug was reported around the world when the clocks changed in different regions, our reporter says.

Apple should have learnt from that example and seen this one coming, he adds. According to the company, the problem will resolve itself on 3 January, but that is two days late for many people.

More than 1.7m people around the world had bought iPhone 4 handsets by June 2010, in what was the company's most successful product launch.