THE iPhone 4 is out of stock in three of the four Apple Stores in Shanghai and Beijing, even after Apple introduced an online pre-order service to keep the gadget from selling out early.

Apple's website showed that only the 32GB iPhone 4 is available in Beijing's Apple Store in Xidan, which means consumers can't get the sizzling-hot smartphone in the three other Apple Stores, 163.com reported yesterday.

From October 8, consumers had to pre-order the iPhone 4 online and then collect it at an appointed time in Apple Stores with proof of ID and a limit of one phone per customer, Apple said.

Analysts said the price of the iPhone 4 in the grey market may go up due to the shortage in official stores.

Apple started to sell the long-awaited iPhone 4 from September 25 on China's mainland. With a more competitive price and no contract requirements, buying the device at Apple Stores is more popular among consumers.

The IPhone 4 is sold at China Unicom and Suning Appliance stores but requires a deposit of 5,880 yuan (US$884) or 6,999 yuan with a two-year contract.