TOKYO, JAPAN: Fans stormed Apple Inc's store in Japan and operator Softbank Corp's outlets as the company launched a slim new version of its wildly popular iPhone.

Due to the time difference in the global launch, Japanese customers were the first to get hold of the coveted iPhone 4, which debuts in the United States, France, Germany and the UK later on Thursday. iPad too was debuted in Japan.

Sales of the iPhone 4, which boasts a higher-quality screen and longer battery life than the previous model, blew past expectations in its first day of pre-orders last week with more than 600,000 of them sold in just 24 hours.

Also read: Apple unveils iPhone 4 to fend off Google

"I can't stop smiling," said Noboru Takahashi, a musician who had waited in line since Monday at Softbank's Omotesando store in a posh shopping district of Tokyo. He was the first in a queue of more than 300 people.

The iPhone has been a huge success since it debuted in 2007, boosting Apple's margins and transforming it into one of the world's leading mobile device makers.

The iPhone, however, faces a slew of new competitors, including Motorola Inc and HTC, designing high-powered handsets based on Google Inc's Android software.

Also read: Vodafone to bring iPhone 4 to India

Demand for the iPhone 4 has been high, but Apple had to apologize last week for having to halt sales temporarily after the surprising volume of online interest overloaded order and approval systems and supplies ran out.

The device, which also offers video chat via WiFi, and a gyroscope sensor for improved gaming, comes less than a month after Apple's iPad went on sale outside the United States.

The iPad, a tablet computer which hit U.S. shelves in April, has already sold 3 million units worldwide.

Up, up and away

For the current quarter, which ends June 26, analysts roughly expect Apple to sell 8-9 million iPhones in total, which includes sales of older generation models. IPhone 4 sales in the current quarter are expected to be limited by supply shortages.

Going forward, analysts expect the company to ship 10 million or more a quarter, as production ramps up to meet demand.

Apple unveiled the slimmer iPhone 4 earlier this month, kicking off its fastest-ever global product roll-out to try to stay a step ahead of rivals in a red-hot smartphone market.

The phone sports chips from Samsung Electronics, Micron Technology, and STMicroelectronics,

according to an early teardown, or disassembly analysis by technology firm iFixit.

"It is very well made as a product and the price is pretty cheap, and the strong pre-orders are the result of that," MM Research Institute analyst Tadayuki Shinozaki said.

"There are not enough supplies to meet demand, especially the LCD panels, though some of that could be a strategic move."

Also read: AT&T suspends preorders of iPhone 4

The iPhone remains Apple's main growth line, and the international market is key. Some analysts estimate more than two-thirds of iPhone sales are now coming from overseas.

Softbank, iPhone's exclusive operator in Japan, suspended taking pre-orders after three days due to overwhelming demand.

The latest phone would be available in 18 countries in July and 88 by September in the quickest-ever international roll-out for an iPhone, Apple had said when it unveiled the iPhone 4.