These are the first teaser pictures of the new Audi A8, which is set to be unveiled later this year.

The pictures were released during Audi's centenary celebrations, and the clearest image, a sketch, shows the front headlamp styling and LED daytime running lights, as well as giving clues as to how the bonnet and grille will look.

The other images issued by Audi are not captioned, but appear to show the new A8's front and rear cloaked under a sheet, and a long-distance shot of two styling models.

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"Right now, the new Audi A8 is undergoing its final stages of fine tuning and is running test laps cloaked in strictest secrecy," said Audi. "For the time being, we can't present you any more than the appetiser outline of a headlamp."

The new A8 has been spied testing around the Nurburgring for several months, but it has always carried heavy disguise.

However, it is clear that the new A8 will use a weight-saving aluminium spaceframe and be around 10cm longer than the current model.

It is also expected to get a cleaner and more efficient range of engines, including 3.0-litre and 4.2-litre V8s.

Audi says the car will be unveiled in late autumn, rather than being shown at September's Frankfurt motor show.

The new Audi A8 is expected to go on sale in the UK in early 2010.

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