More than 100 mature specimens, around 300 years old, are believed to have been cut down in the past three months across Ceredigion and Carmarthenshire.

If this continues, Wales stands to lose a significant number of prize specimens, which are irreplaceable

Forestry Commission's Steve Hunt

Bogus tree cutters who claim they are from the council are thought to have been approaching landowners and farmers and warning that nearby trees are damaged or dangerous.

They then offer a felling and extraction fee of around £200 to remove them.

But the cutters do not have the appropriate licence to cut down the trees.

In order to cut trees down trees over a certain size, a special permit is required from the Forestry Commission.

Officials stress that the owner remains liable and can face prosecution for illegal felling, irrespective of who fells the tree.

It is reported that the people responsible are approaching landowners and claiming to be from the council

South Wales Police

"It is understood that these illegally felled, veteran oaks may be being shipped abroad, possibly to the US," said Forestry Commission spokesman Steve Hunt.

"If this continues, Wales stands to lose a significant number of prize specimens, which are irreplaceable in our lifetime and for centuries to come.

"We would urge all landowners and local communities to be extra vigilant on this matter," added Mr Hunt.

A spokesman for Dyfed-Powys Police spokesman said that police are investigating a report of illegal felling.

"It is reported that the people responsible are approaching landowners and claiming to be from the council," confirmed police.