Over half a million ounces of gold have been discovered underneath the surface at Clontibret, Co Monaghan, at an average depth of 150 metres.

The announcement was made by mineral exploration company Conroy Diamonds and Gold (CDG), which made the original discovery that led to the establishment of a lead zinc mine at Galmoy, Co Kilkenny, which is now being mined by Arcon.

The news is "highly encouraging as it demonstrates real commercial feasibility", according to Professor Richard Conroy, chairman of Conroy Diamonds and Gold.

"We have had our findings confirmed by the industry as a whole. There is more research to be done but we will be applying for a mining licence and planning permission in the near future. It is possible Ireland could become a large producer of gold in the next 20-odd years, ' the former Fianna Fáil senator told the Sunday Tribune.

However an industry source cast doubt over the project because it is not yet of a high enough grade and needs more research.

"It is good that we have this amount of gold but it runs over 50 kilometres.

More of it needs to be found in one place and at a higher grade. While it is good news its very much early stages, " the source said.

Preliminary estimates put the cost of extracting the gold at $350 an ounce, with the current market value of gold approximately $600 an ounce.

CDG is set to look for a venture partner to get involved in the project.