While Apple's iPhone is selling well across the globe, China has emerged as its fastest growing market for the device.

In a conference call on Wednesday, April 21, Apple Chief Operating Officer Tim Cook, said that for the first three months of 2011, iPhone sales in "Greater China" grew by almost 250 percent from the same period last year. This brought Apple's revenues in the first fiscal half to just under US$5 billion for the Greater China market, an increase of almost four times from 2010, IDG News Service reported.

The $5 billion generated represents about 10 percent of Apple's revenues, Cook added in the conference call. "So we're extremely happy with how we're doing in China," he said. In the U.S., iPhone sales grew by 155 percent.

It's unclear, however, where in China the device is selling the most. Cook's reference to Greater China includes the mainland, Hong Kong and the island of Taiwan, said Apple spokeswoman Carolyn Wu.

But analysts have said that in mainland China, Apple is seeing a major shift with how consumers are viewing the iconic smartphone. When Apple's iPhone 4 launched there in late September, it was a hit with Chinese consumers, quickly selling out and leading to shortages.

Earlier versions of the iPhone had not met with the same reception, said Mark Natkin, the managing director for Beijing-based research firm Marbridge Consulting.

Apple didn't officially begin selling the iPhone in mainland China until late 2009, more than two years after it was launched in the U.S. Even then, the iPhone sold in the country was designed without Wi-Fi capability, in order to comply with Chinese technology regulations at the time.