Apple on Wednesday introduced its new iPhone 5 -- a lighter, thinner and more powerful version of its iconic mobile device, staking its claim to leadership in the red-hot smartphone market.

Apple chief executive Tim Cook called the launch 'the biggest thing to happen to iPhone since the iPhone.'

The company called the iPhone 5 'the thinnest smartphone in the world,' with an anodized aluminum body that is 18 percent thinner and 20 percent lighter than iPhone 4S.

It features 'diamond cut chamfered edges and glass inlays for a truly incredible fit and finish,' an Apple statement said.

At a packed launch event in San Francisco, Apple marketing chief Phil Schiller said of the new iPhone: 'It is an absolute jewel. The software and engineering that went into this product is the most challenging our team has ever taken on.'

Apple will start taking orders for the phone Friday and begin shipments September 21 in the US, Canada, Britain, France, Germany, Australia, Hong Kong, Singapore and Japan, and the phone will be available in 100 countries by the end of the year.

Pricing for US customers will start at $199 with a two-year contract.

The introduction has been among the most keenly anticipated in the tech world, with rumors and leaks over several months about the new device from the biggest company in the sector.

Schiller said .