Authorities in Northern Ireland are considering starting the planning process again to build the North-South Interconnector, the Minister for Communications has said.

Earlier this month, a group of landowners in the north won their legal challenge to approval being given for a new cross-border electricity line.

A group formed under the name Safe Electricity A&T (SEAT) issued proceedings to claim the move was unlawful.

Their lawyers contended that a development of such regional significance needed to be signed off by a minister.

The challenge centred on the legal power of civil servants to take decisions without a functioning executive at Stormont.

Today, the Supreme Court in Dublin upheld a High Court ruling over An Bord Pleanála's granting of permission for the planned North-South Interconnector.

This evening, Fine Gael Senator Joe O'Reilly and Green party leader Eamon Ryan asked Richard Bruton about the Eirgrid interconnector project that comprises a 400kV overhead line circuit linking an existing substation in Woodland, Co Meath, with a planned substation in Turleenan, Co Tyrone.

Mr O'Reilly, from Co Cavan, asked what the implications for the project would be if Britain crashes out of the European Union and there is no Brexit deal.

He asked if a new single energy market agreement between north and south would have to be agreed in that scenario.

Mr Bruton pointed out that if there is an agreed withdrawal, the north-south single market is recognised in the Withdrawal Agreement.

He added: "In the event of a crash out there are certain trades that occur on the single electricity market that will no longer occur.

"However, the expectation that the remaining trades, the security and supply trades and the intra-day trades will continue to support pretty normal business on the system."

He indicated that "it won't lead to any short term problems" and under Brexit contingency legislation the Commission for Regulation of Utilities will be given the power to alter licences and ensure the market is protected.

The minister acknowledged that a new deal will need to be worked out. He cited the example of the integrated energy markets in Finland, Norway and Sweden.

Specifically on the North-South Interconnector he said: "The position as I understand it is that our Supreme Court cleared the project in the south this morning, but as Eamon Ryan has said, in Northern Ireland last week the state withdrew the application in light of the fact that there is this flaw in not having a ministerial presence.

"However, they have introduced new legislation which allows the secretary general provide the necessary approvals and it would appear that they are now considering starting the process again."

He said he cannot be categorical about what the next steps in the planning process will be.

The Green party leader asked if it is true that there is a risk of electricity blackouts in Northern Ireland in 2021 if the interconnector is not in place?

Mr Bruton said he did not want to be categorical but his understanding is that they do have standby plants that they can bring into operation.

He said that these "may not be the ideal plants, as they are coal-fired plants" but they do have plants that can be brought back into play that had previously been identified for decommissioning. 

He said that the UK seems to recognise the importance of being interconnected to the EU market.

Sinn Féin TD Brian Stanley and Fianna Fáil TD Timmy Dooley asked about World Trade Organisation tariffs being applied to gas and electricity post-Brexit.

But Mr Bruton said that WTO tariffs are not applied to gas and electricity so the price of the two utilities will not be affected in a no-deal crash out scenario.