Roman chariots once used the track to clatter across the moor on their way to keeping down the tribes.

Now motorbikes and 4x4 vehicles roar along it, churning up and destroying a thousand years of history.

And countryside campaigners have had enough.

They want the old route - from Middleton near Ilkley, North-North-East over Langbar Moor and Blubberhouses Moor to the church in Blubberhouses - barred to sports off-roaders vehicles before it vanishes completely.

But, at the moment, the law states that where chariots once drove Jeeps are at liberty to follow. Mike Bartholomew, chairman of the Yorkshire Dales Green Lanes Alliance, said: "Eighteenth century law states: 'Once a highway, always a highway' and that spells disaster for us.

"When off-roaders realise they've discovered a lost highway they must throw their crash helmets in the air with joy.

"Just because it was once open to horse and carts or chariots means they could drive a double-decker bus down it if they wanted to."

So the alliance's membership of walkers, cyclists, fell runners, horseriders and landowners, has called for a change of the outmoded law to give access to green lanes only to farmers and landowners, walkers and cyclists.

A Government consultation about the problem nationwide is underway as part of the Countryside and Rights of Way Act 2000. For, according to Mr Bartholomew, of Otley, there are hundreds of green lanes at risk across The Dales.

He said the "off-riders" are destroying fragile surfaces, disturbing ground-nesting birds, shattering peace and tranquility and wrecking the countryside's heritage.

The alliance is lobbying for prosecutions if sports drivers stray on to restricted byways.

Mr Bartholomew said: "The Dales are becoming an arena for boys and toys. They don't care for the countryside, they just ride in circles in search of excitement. Where once you could hear the sound of curlews and oystercatchers, all you can hear now is the roar of engines.

Gordon Woodhead, chairman of Bradford Ramblers' Association, said one of the most recent problems was on the old highway from Oxenhope to Hebden Bridge.

He said: "We can't legally do anything about it. A lot of tracks are now unfit because off-roaders have left them in such a state. The other danger is that these vehicles come flying out of nowhere and the terrain means they don't always have good control."

But Sue Smith, secretary of the Auto Cycle Union's Yorkshire Centre, said most trail riders belong to organised clubs and stay friendly with farmers and landowners.

There are some who would ride anywhere, though, she said. They stray off lanes, scaring sheep and upsetting people: "They give the rest a bad name."

Andy Green, chairman of the Trail Riders' Association of Craven, whose code of conduct respects the countryside and its users, said: "Banning legal riders from green lanes will encourage the illegal riders who have no respect for either the law or the countryside to increase in numbers."

But he said: "Walkers have access to all the lanes; we only use five per cent so, if they don't want to see us, why don't they use the ninety-five per cent?"

And, he said, when advised by officials not to use certain lanes, his club puts up signs to alert riders of the detour: "But these are torn down by walkers; we can't win."

A Bradford Council spokesman said: "The Council is waiting for the outcome of the public consultation and publication of Government guidelines before deciding if any action needs to be taken."