The new Apple iPhone 4 may have sold out both in the US and in the UK and customers will have to wait until 2 July to get their hands on a Sim-free iPhone 4.

Apple made the unlocked version of its latest smartphone available for pre-order through its online store yesterday, at the same time as announcing the pricing.

Initially, Apple's website claimed the company would ensure the handset would be delivered on 24 June. However, just 24 hours later, Apple's website is stating 2 July as the delivery date.

The 16GB iPhone costs £499, while the 32GB handset is priced at £599. Apple did not reveal the price of the black version of the smartphone.

Meanwhile in the US, Apple's preordering system for the iPhone 4 appeared overloaded or broken on Tuesday according to reports. Thousands of those that visited Apple's preorder page at received the message "There was an error processing your request. Please try again later," at around 5:45pm ET. Similar error messages were being coughed up from AT&T's preordering page. Apple's customer service line 800-MYAPPLE was also experiencing problems delivering the recorded message "due to heavy call volume, we cannot take your call at this time."

This is not the first time that Apple has shifted the delivery days due to unprecedented demand. Last month, when Apple made the iPad available for pre-order in the UK, it pushed back the shipping date from 28 May to 7 June.

The news comes as Tesco Mobile announced it will also stock the iPhone 4.

Like most of the other UK networks, Tesco has very little information on pricing details of the handset. Instead it's encouraging those interested in Apple's latest smartphone to register for more information on a dedicated web page. However, it does claim the handset will be available from June 24.

Tesco is over a week behind O2, Orange, T-Mobile, Vodafone and 3 in announcing it will stock the handset.

Apple's latest smartphone was unveiled by Steve Jobs last week at the company's Worldwide Developers Conference (WWDC).

The new handset, which features an all-new design, has "well over 100 new features" including an HD screen, video calling, a gyroscope, a new iMovie app and countless other upgrades.