San Francisco - Apple unveiled a new line of Macbook laptop computers Tuesday, bringing prices down at the same time as improving function and design.

The two most prominent new features of the new line-up are powerful new graphics capabilities provided by Nvidia chips that replace integrated Intel graphics chips that were used previously. Apple CEO Steve Jobs said the new chips improved graphics performance by a factor of five.

Jobs also touted a new manufacturing process that allows the laptop cases to be made from a single block of aluminium.

"Apple has invented a whole new way of building notebooks from a single block of aluminum. And, just as important, they are the industry's greenest notebooks," said Jobs. "The new MacBooks offer incredible features our users will love - like their stunning all-metal design, great 3D graphics and LED backlit displays - at prices up to 700 dollars less than before."

Apple said that in addition to providing MacBooks with a sleeker design,the new manufacturing process has made the computers, thinner, stronger and better able to withstand impacts. The MacBook Pro also comes with a newly designed trackpad. The multitouch glass trackpad has a 39 per cent larger tracking area than before, according to Jobs, and the entire trackpad will act as button.

The new MacBooks also feature an LED-backlit display that uses 30 per cent less energy than its predecessor and eliminates the mercury found in fluorescent tube backlights.

The new MacBook line starts as 1,299 dollars in the US with prices rising to 2,499 dollars for the top of the line MacBook Pro.