Sales of the new iPhone 5 could be double those of the previous model in its first week on the market, thanks to Apple’s most aggressive smartphone launch plan yet, and as many as 33 million iPhones might be sold this quarter, analysts said.

Many expressed surprise at how quickly Apple planned to roll out the new model around the world, saying this showed that supply constraints afflicting past releases would not be a problem this time for the faster and slimmer iPhone 5.

The new model ships on Sept. 21 in the United States, Australia, Canada, France, Germany, Hong Kong, Japan, Singapore and Britain, and will hit 100 countries by the end of the year in the fastest international rollout for an iPhone so far.

While many Apple watchers said the new iPhone lacked a “wow” factor, Apple shares rose after the launch, in contrast to a fall after the launch of the previous model, the 4S, almost a year ago.

“We are positively surprised that this iPhone rollout is Apple’s fastest yet,” Barclays Capital said in a client note, adding that it had previously thought supply constraints for sensors in the new screens would hold back initial sales. “Given this pace it would seem Apple is very well positioned for upside in the December quarter.”

Apple shares rose nearly 2 percent to close at about $683 in heavy trading Thursday on the Nasdaq.

The iPhone 5 sports a four-inch “retina” screen that displays a sharper image. It can run on high-speed 4G LTE wireless networks and is 20 percent lighter than the iPhone 4S.

“While it lacked the mind-blowing innovation we have come to expect of Apple, [it] is differentiated enough to maintain a sizable product advantage over its competitors,” said FBR Capital markets, the brokerage that is forecasting Apple’s shares to hit $1,000 within the next year.

Brokerages raised their sales estimates for the September quarter from anywhere between 3 percent to 36 percent, with most expecting between 20 million and 30 million iPhones to be sold.

RBC Capital said sales of the iPhone 5 this month could result in additional sales of $4 billion to $5 billion for the quarter ending Sept. 30. The brokerage increased its price target for the stock by $50, to $750.

Barclays, which raised its price target for Apple stock to $810 from $750, said Apple would have a “unique holiday season” as it would also benefit from upcoming launches of a smaller iPad and new Mac computers.

Credit Suisse forecast 20 percent growth in high-end smartphone sales next year, with Apple grabbing a 47 percent share, topping archrival Samsung Electronics with 40 percent.

It picked the two companies to capture just over half of the overall smartphone market, putting “tremendous pressure” on Research In Motion’s BlackBerry, as well as other offerings from Nokia and less-sophisticated smartphones that use Google’s Android software.

— Reuters