NEW YORK, USA - ACTIVATION problems marred the United States launch of Apple's new iPhone on Friday, with many eager buyers leaving stores frustrated that they could not use the hotly anticipated gadget after waiting in line for hours.

AT&T, the sole US carrier for the iPhone, blamed problems synchronising the phone with Apple's iTunes online music and software store, saying it was probably caused by too many people trying to access iTunes at the same time.

Apple had no immediate comment on the problem, which appeared to be affecting users of the older iPhones as well.

AT&T spokesman Michael Coe said Apple was working to resolve the problem, but he had no timeframe.

'There's been a lot of demand worldwide for the iPhone 3G,' Mr Coe said. 'That means a lot of people synching with iTunes.'

AT&T, which was still selling phones by mid-afternoon after selling out in some stores, advised customers to go home and activate the phone later themselves on iTunes, Mr Coe said.

Some customers at the Apple store in New York's SoHo said Apple employees had told them the problem was with AT&T's network. Mr Coe said he was unaware of any AT&T problems.

Old iphones affected
Earlier on Friday, many customers had left stores pleased it had taken only 15 minutes to activate their new iPhones, which combine a music and video player, phone and Web browser.

'It's really great, it's a lot better than my BlackBerry,' said Mr Joshua Deutch, 31, referring to the e-mail device made by Canada's Research in Motion that is popular with corporate users.

'Launching a website takes seconds ... It's very comfortable,' Mr Deutch said. 'I'm trying to get it up on my firm's e-mail and there are some hiccups here and there. But overall, it's a good experience.'

But by mid-afternoon, many customers were being sent home without having activated their phones.

Some users of the original iPhone and iPod Touch, both launched in 2007, also said they were having difficulties downloading software updates so they could play video games and use other applications on their software.

While some cheerfully accepted that hiccups were to be expected during a big product launch, others were annoyed.

'My phone's not working. So now my old phone doesn't work and my new phone doesn't work. I'm going to have to find a pay phone. Do they still make pay phones?' said Ms Deena Hadi, 23, a marketing analyst at the Fifth Avenue store in New York.

Mr Ben Gersch, 31, a New York artist, said the initial set-up had been slow in the Apple store in SoHo, but that it had begun working from the moment he left. 'It sounds good, it's fast, it's like having a laptop with you,' he said.

In California, Mr Dana Hense emerged from the Palo Alto Apple store with three iPhones - one for himself, one for his wife, and one for his 11-year-old son.

The 35-year-old software programmer for Web performance measurement company Keynote Systems said he had endured nearly three hours of frustration getting the new phones authorised with his son and younger daughter.

Asked it if was worth the wait, Mr Hense said, 'I can't tell you yet.'