The BBC is fighting to keep Top Gear's mystery driver The Stig from revealing his identity.

The corporation has launched a legal bid to stop the faceless show favourite - who speeds around a race track with a blackened visor - writing his autobiography.

BBC lawyers claim he is subject to a confidentiality agreement and unmasking himself would spoil viewers' enjoyment of the BBC2 programme, which is one of the channel's most popular.

The Stig famously takes to the track in an assortment of cars, as well as training celebrities to set lap times in Top Gear's popular "Star in a Reasonably Priced Car" segment.

According to the BBC, his autobiography breaches "agreed contractual and confidentiality obligations" relating to the programme".

Clad in race overalls and a helmet, the driver's identity has long been a closely-guarded show secret, spawning T-shirts emblazoned with slogans like "My Dad is The Stig".

Only a handful of executives and 'Top Gear' presenters Jeremy Clarkson, Richard Hammond and James May are said to know who he is.

Several racing drivers have been linked to the role, including former Formula One world champions Damon Hill and Michael Schumacher.

Clarkson and his fellow presenters have all enjoyed spin-off success from 'Top Gear', such as books and other TV work.

The current Stig is the show's second. The original, Perry McCarthy, was dropped after his identity was discovered.