According to one Welsh farming union, a recently re-enforced law means some farmers are incurring fines for moving animals on land they consider their own. The Farmers' Union of Wales warned earlier in December that farmers with areas of sole grazed common land may have to register links between their holdings and that land - or risk penalties for moving animals on their own farms.

The warning was issued after one Welsh farmer was fined for moving animals between adjacent fields on his farm. The union said its Denbighshire chair, Arthur Roberts faces a fine for moving sheep on between fields only used by him, but which are officially "CL99 land".

Rules on common land state farmers should notify the authorities of any moves between their own land and that common land; FUW said many Welsh farms include normal fields registered as common land, although they are no longer shared. Although the union described the situation as "ridiculous," the Welsh government has maintained exemptions are available.

FUW said a recent change of policy has meant the government has begun enforcing rules requiring farmers to register movements of animals between registered and unregistered fields within a farm. The union said movements must be reported or the Welsh Government must be notified of a link between the fields.

Mr Roberts, who farms near Pentrefoelas, said, "The fields on this farm are no different to those on any other except that part of the land is registered as common land for historical reasons. None of it is shared grazing and the land in question is just a stone's throw from the farmhouse. I could not believe it when we were penalised."

The government maintains Mr Roberts should have registered a link between the fields. A spokesperson said that the union had been made aware of the rule change in guidance information published in 2008 and 2010.

FUW agricultural policy director Nick Fenwick said "We are aware of many farms where fields or parts of fields are registered as common land, often due to mapping errors. They are known as CL99 areas and have caused numerous problems for years but we never imagined that the Welsh Government would start treating these areas as separate holdings for the purpose of movement recording and reporting."

The rules cover land that may have been used to graze animals from several holdings, and the government said it is enforcing this regulation as it is useful in disease surveillance and animal welfare cases.

"We have made numerous representations to the Welsh Government since March but they are adamant that they will not reverse the policy. We are currently seeking legal advice and have asked for an urgent meeting with the Chief Vet, but in the meantime farmers should register links with all common land which forms part of their holding."