Apple says it sold more than 1.7 million of its new iPhone during the three days after the phone hit shelves on June 24 amid a major launch of competing smartphones on T-Mobile USA, Verizon Wireless and Sprint.

Calling the iPhone 4 “the most successful product launch in Apple’s history,”Apple CEO Steve Jobs admitted that the company was struggling to meet demand for the device. “Even so, we apologize to those customers who were turned away because we did not have enough supply,” he said.

On June 16, Apple said it had received 600,000 pre-orders for the iPhone 4. The massive influx of orders was 10 times higher than last year’s sales of the iPhone 3G S and wreaked havoc on AT&T’s and Apple’s websites, crashing AT&T’s system and causing major malfunctions in Apple’s ordering program.

The iPhone 4 launch was also marred by an apparent antenna glitch which causes the device to lose 3G, Wi-Fi and Bluetooth reception when a user’s hand touches the left-hand portion of the device’s external steel antenna. The problem is apparently solved by attaching a protective case or one of the rubber bumpers being sold by Apple.

Apple’s sales announcement came as T-Mobile USA, Verizon Wireless and Sprint announced the launch of three high-powered Android 2.1 devices from Samsung.