An Bord Pleanála has been condemned by environmental group An Taisce for granting planning retention to a sawmill in Co Offaly.
T&J Standish Sawmills, one of the Republic's largest suppliers of pencil stakes and fencing products, was originally refused retention permission for its factory by Bord Pleanála in July 2003.
The sawmill is located beside Leap Castle, a protected structure and national monument built by the Carroll family in the 16th century.
The company has been successfully prosecuted by the Environmental Protection Agency (EPA) for breaches of its licence. Earlier this year, the Office of Environmental Enforcement warned farmers in the area not to dredge a local river because of pollution from the plant.
The historian Prof Roy Foster, the Irish Georgian Society, An Taisce and the Aghancon Concerned Residents' Association appealed the original retention permission for T&J Standish Sawmills Ltd to An Bord Pleanála.