Under the £1bn deal, Republic’s power supply company ESB will buy the transmission and distribution business Northern Ireland Electricity.

The takeover deal is expected to be sealed at the end of the year after Irish and UK competition clearances and a refinancing of  debts at the Northern Ireland parent company Viridian .

NI Energy Minister Arlene Foster said she had already discussed the transaction with the regulator and the Irish Minister Eamon Ryan.

“I have received assurances from ESB on a range of issues relating to the transaction.

“These include ESB investment plans, the importance of securing existing jobs, and maintaining the identity of the electricity network business in Northern Ireland.

“I will continue to keep a close watch as the transaction proceeds towards completion, to ensure the interests of electricity consumers in Northern Ireland are being properly considered.”

NIE employs 1300 staff and is owned by the Viridian Group, which runs the generation and supply business Energia, and operates windfarms and the Huntstown power station in north Dublin.

NIE’s ultimate owner is Arcapita, a Bahrain-based bank, which bought Viridian in 2006 for more than £1.6bn.