Apple's new iPhone 3G S smartphone has sold more than one million units in its first three days on the market.

The company said that the new iPhone hit the sales milestone on Sunday, less than 72 hours after the first units went on sale.

The speed with which the 3G S reached the one million mark matches that of its predecessor, the iPhone 3G, which also eclipsed one million sales three days after its international launch. The first iPhone handset needed some two and a half months to hit one million sales.

Apple said that its new iPhone 3.0 software had been downloaded by more than six million users. The free update adds several new features to the iPhone, as well as new capabilities for developers.

The sales are good news for Apple in what promises to be a busy and competitive summer for smartphone vendors. Earlier this month Palm launched its Pre handset, and several vendors are preparing new Android handsets.

In one of his first public statements since leaving the company with medical problems in January, Apple co-founder and chief executive Steve Jobs applauded both milestones.

"Customers are voting and the iPhone is winning," he said."With over 50,000 applications available from Apple's revolutionary App Store, iPhone momentum is stronger than ever."