An Irish gold mine should be made to stop working underground because it was allowed to expand based on inaccurate maps, it has been claimed.

Omagh Minerals, a subsidiary of the Canadian firm Galantas Gold Corporation, was given a green light to extend its mine by Mark Durkan, the Northern Ireland minister for the environment at the time, in 2015, as long as it complied with strict environmental conditions.

William Donnelly, who runs a bed-and-breakfast near the mine, told the Court of Appeal in Belfast on Thursday that more than 20 hectares of the site, at Cavanacaw, in Co Tyrone, were never properly assessed. He claimed that the mine operator's planning application was for 60 hectares but that maps and drawings submitted as part of the process covered 81 hectares. He said that raised the possibility that the minister was "misinformed or even confused as to the scale of the project being approved".

Mr Donnelly, whose challenge to the minister’s decision was dismissed by the High Court last September, also alleged that Omagh Minerals had removed large quantities of rock without permission and that the waste rock could be acidic and therefore environmentally damaging.

Lawyers for the department argued that the mine was covered by planning approval obtained more than 20 years ago and that no regulations were breached during the decision-making process.

Lord Chief Justice Sir Declan Morgan said he would making a ruling as soon as possible.