Long queues formed outside stores such as Apple and O2 ahead of the launch of the iPhone 4.

The smaller, lighter version of the iPhone went on sale at 7am at Apple stores today.

Official sales figures have not been released. An O2 spokesperson said: “We still have stock in the majority of our stores but we expect to sell out by the end of the day.”

O2 put a note on its website telling shoppers that iPhone 4 stock is limited in the UK at launch and only existing customers would be able to get the new phone until at least the end of July.

Other retailers such as Phones 4u, T-Mobile, Orange, O2, Vodafone, Carphone Warehouse and Tesco are also selling the iPhone 4.

Apple’s iPhone 4 will go on sale in America, France, Germany and Japan on June 24.