Police in Huddersfield are urging off-road bikers to keep away from historic land at Castle Hill.
And they are increasing patrols after a number of reports of bikers causing distress to the public.
Officers warned that if bikers are caught riding in an anti-social manner they could have their machines seized.
Huddersfield police posted on Facebook: “Castle Hill is a very special site and riding motorbikes causes damage and is dangerous. Please be aware that motor cycle officers are patrolling the area and will deal with any offending vehicles.
“Bikers please be aware that riding on land not forming part of a road is an offence unless you have the express consent of the land owner.
“This is not permitted and is causing distress to members of the public.”
Anyone who sees off-road bikers at Castle Hill should contact police on 101.
