MOTOCROSS riders who are destroying some of the world's most important bird breeding grounds were told today: "Stop now or face a £20,000 fine".

Landowners, members of Burnley Council and officers from Pennine police are stepping up their campaign to stop the bikers vandalising special wildlife protection areas in Worsthorne and Clowbridge, Burnley.

The area is home to a number of endangered bird breeds and is designated an area of European and international importance because of its large population of twites, merlins and peregrine falcons.

They also form part of the South Pennines Site of Special Scientific Interest.

Lancashire conservation officer for the Royal Society for the Protection of Birds Tim Melling said: "Because of the designation and the new Countryside and Rights of Way Act fines of up to £20,000 can be imposed if people cause reckless disturbance and they have already been told that they should not be disturbing the area. I would support the land owners in taking any action."

Wading birds are especially in danger as precious wetland used by them is being dug up by the bikes.

PC Glenn Grey, of Burnley Police, said: "Access to motor vehicles is strictly prohibited in the Worsthorne and Clowbridge areas.

"However, some days there can be up to 20 bikes scrambling on the land which is causing considerable problems, not only for local wildlife, whose habitat is being disturbed, but also for farmers who have livestock nearby and walkers, pedal cyclists and horse riders.

"From now on, anyone caught misusing the land will receive a warning letter which will go direct to the registered owner and keeper of the bike. There will be no second chances -- persistent offenders will face hefty fines."

Countryside ranger Glynn Haworth works for United Utilities, who own the land.

He said heartless bikers were continuing to destroy important habitat despite repeated attempts to stop motocross and trial bike riders from regularly using the areas.

Mr Haworth said: "Apart from the noise and disturbance which terrifies the birds, the rutting of the land caused by the bikes channels water, reducing the amount of precious wetland for the wading birds such as dunlin and snipe."

He added: "The moors are a precious haven for their natural habitats and wildlife.

"Birds such as peregrine, twite and short-eared owl make their home on the moors and the blanket peat with its cotton grass, heather and marshy pools is nationally important."

Up to 25 to 30 motorbikes a day are used for scrambling on the moors scarring the landscape and frightening wildlife as well as farmers' livestock.

He said: "The area is popular with walkers, families, horse-riders and mountain bike cyclists who all have every right to be there and enjoy the peace and beauty of the moors.

"The motorcyclists are destroying that peace and beauty for everyone on land they have no right to enter."

Warning signs have been ignored or even knocked down .

Mr Haworth added: "As the bikers don't seem to care about destroying the environment and harming wildlife hopefully they will care about being prosecuted and having their bank balance reduced."

Worsthorne councillor Kevin Robinson believes that the riders are operating as an organised gang, and has only one message for them.

He said: "Stay away. They are upsetting the wildlife, the fauna and the residents who live nearby.

"They are absolutely wrecking the ground that they are riding over. They are wrecking footpaths and pastures -- everything.

"I am totally against them and will keep pushing this issue. I want it sorted. They are ruining the countryside."

Worsthorne Moor was one of the first public access areas to be set up in the UK and dates from 1956.

The moors are a water catchment area owned by United Utilities.