Eirgrid has told public representatives in two of the counties where a new electricity interconnector is proposed that putting the power lines underground "is not technically feasible".
The North South Interconnector would connect the electricity grids of Ireland and Northern Ireland with a 138 kilometer line through Meath, Cavan, Monaghan, Armagh and Tyrone.
It would see 401 pylons erected along the line.
The plans have been met with local opposition for many years, with repeated calls from local people, landowners and public representatives for the lines to put put underground.
CEO Mark Foley briefed county councillors in Monaghan and Cavan about the plans yesterday, telling them that the project will now move into the construction phase.
He said that technology options are assessed for each of Eirgrid's projects and that each project is different.
Mr Foley said that where it is feasible, they would underground projects.
However, councillors were told that it was not technically feasible for the interconnector to be placed underground.
'Standing with the community'
Mr Foley said this was because it "carries too much power, over too long a distance and the infrastructure is far too critical".
Speaking following the meeting, Cathaoirleach of Monaghan County Council Seán Conlon said that people are almost unanimously in favour of the interconnector being built but not in its current form.
He said that the 18 members of the chamber were "standing with the community" and were in "unanimous opposition" to the plan and want the electricity interconnector to be undergrounded.
Mr Conlon said he did not believe that Eirgrid addressed questions raised at the meeting about the potential for confrontation with landowners.
A motion was passed calling for the Government and Minister Eamon Ryan to carry out a full independent appraisal of the undergrounding of the project.
The meetings with the two county councils yesterday were also told that it was essential the the project proceed "without any further delay".
A compensation package is being prepared for landowners affected, and Eirgrid told the meetings it would fully engage with landowners, local communities and other stakeholders along the route.
"The development of a comprehensive and fair compensation scheme for landowners hosting the infrastructure is being prioritised.
"This project is a piece of critical infrastructure and Eirgrid and the ESB will be using all mechanisms at our disposal to ensure delivery," said Michael Mahon, Chief Infrastructure Officer with Eirgrid.
A community benefit scheme is also planned.
