Apple said Wednesday on the eve of the launch of the new iPhone that the white model would not be available for a month, the latest manufacturing glitch for the California gadget maker.

Apple said the white version of the iPhone 4, which also comes in black, was being delayed because of unspecified manufacturing difficulties.

White and black model iPhones had been scheduled to go on sale in stores in Britain, France, Germany, Japan and the United States on Thursday and Apple fans are already queuing up to buy the latest generation of the popular device.

But Apple said customers who want the iPhone with the white case will have to wait.

"White models of Apple's new iPhone 4 have proven more challenging to manufacture than expected, and as a result they will not be available until the second half of July," the Cupertino, California-based company said.

"The availability of the more popular iPhone 4 black models is not affected," Apple said in a brief statement.

There was no immediate reply from Apple to a request from AFP for details about the problems with the white model iPhones.

The delivery delay for the white iPhone 4 comes two months after Apple was forced to put back the international release of its new touchscreen tablet computer, the iPad.

Citing demand in the United States that was "far higher than we predicted," Apple in April delayed the release of the iPad outside the United States for a month.

Apple chief executive Steve Jobs said at the time that Apple was "making (iPads) as fast as we can" but "evidently we can't make enough of them yet."

Apple said this week that it has sold three million iPads since the tablet computer went on sale in the United States on April 3 and nine other countries in late May.

The release of the iPhone 4 has been particularly turbulent for Apple, featuring a troubled pre-ordering process and a sneak preview of the device on the Internet after it was obtained by technology blog Gizmodo.

Apple and its wireless carrier AT&T were forced to suspend pre-ordering of the iPhone 4 last week amid heavy demand.

Apple said it had received a single-day record 600,000 orders for the new iPhone, which features video chat, can shoot and edit high-definition quality video and has a crisper resolution screen than previous models.

AT&T, the exclusive carrier for the iPhone in the United States, said pre-order sales for the iPhone 4 were "10-times higher than the first day of pre-ordering for the iPhone 3GS last year."

AT&T said meanwhile that it would be able to deliver iPhones on Thursday to customers who pre-ordered the device but they would not be available for sale in AT&T stores until next week.

Apple stores in the United States will offer the black model on Thursday.

The new iPhone 4 costs 199 dollars for the 16 gigabyte model and 299 dollars for the 32GB version.

Analysts are expecting another hit for Apple.

"Initial demand for the new iPhone is incredibly robust," Deutsche Bank analysts Chris Whitmore and Joakim Mahlberg said. "We anticipate another Apple event' with long lines, heavy store traffic and stock outs."

Apple has sold more than 50 million iPhones since it launched the device in 2007.

Apple shares were down 1.34 percent at 270.17 dollars shortly before the closing bell on Wall Street on Wednesday.