Hundreds of fans flocked to stores in Tokyo to be the first buyers of Apple's iPhone 4 and some lined up in San Francisco as the red-hot smartphone rolls out on Thursday in five of the world's six largest economies.   

Sales of the iPhone 4, which boasts a higher-quality screen and longer battery life than the previous model, have blown past expectations, overloading systems and causing Apple and carriers to halt taking pre-orders as supplies run out.

In Japan, where the gadget was launched before other countries due to the time difference, fans dressed up like iPhones and painted iPhones on their faces.

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

The iPhone has been a huge success since it made its debut in 2007, boosting Apple's margins and transforming it into one of the world's leading mobile device makers. However, the supply shortage, which an analyst said was worsened by a lack of LCD panels, could cap initial sales and hurt Apple when it faces a slew of new rivals, namely high-powered handsets based on Google Inc's Android software.
   
"The Droids are coming and current demand for the iPhone 4 implies a titanic battle between Apple and Google is imminent," industry tracker comScore said in a statement.

Apple has announced sales of more than 600,000 iPhone 4s, a record for just a single day of pre-orders last week, meaning it sold seven of them per second.

The iPhone is Apple's main growth driver, and is expected to soon become its biggest source of revenue as the company expands the smartphone around the globe. Some analysts estimate more than two-thirds of iPhone sales now come from overseas.

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 and has beaten sales expectations.   

The iPhone 4 debuts in the United States, France, Germany and the UK later on Thursday. -Reuters