A group of landowners challenging plans to build hundreds of pylons across three counties claim the EirGrid application is invalid.

It comes as a planning hearing continues into whether the pylons should be built as part of the proposed North/South interconnector project.

The North East Pylon Pressure Campaign Ltd represents 188 landowners in counties Cavan, Meath and Monaghan.

Last year, EirGrid submitted a planning application to erect overhead pylons across their land as part of a cross-border electricity interconnector.

The campaigners believe the project poses significant environmental and health risks. They are also concerned about the devaluation of their land if 400,000 volt pylons are built.

An oral hearing involving planning inspectors began earlier this month after the group was denied an injunction to prevent the development from going ahead.

They are now challenging the validity of the application itself in the High Court by claiming EirGrid does not have the statutory powers to carry out the works.

Counsel for the Minister for Communications claims their legal action is out of time, and has asked for an adjournment to deal with accusations of bias on the part of An Bórd Pleanála.