The new phone went on sale across Asia and Australia with mobile carriers reporting record demand that looked likely to stretch Apple's supply capacity.

Apple has booked more than 2 million pre-orders for the device in the first 24 hours, double the first-day sales of the previous iPhone 4S.

Its rival and component supplier, Samsung Electronics Co, moved to spoil the party on the eve of the phone's debut, saying it planned to add the new device to existing patent lawsuits against the US company.

The new phone has a larger, 4-inch screen and is slimmer and far lighter than the previous model. The iPhone 5 supports faster 4G mobile networks and also comes with a number of software updates, including Apple's new in-house maps feature.