The ESB's profit after tax increased by 33% in 2015 to €286m, €71m higher than the previous year.

The firm has benefitted from cost savings of €270m per year and increases in the amount of time that its power plants are available to operate.

A dividend of €214m was paid to the Government at the start of this year - this brought the total amount paid to the State during the past decade to €1.5bn.

The company's capital investment fell by €87m on 2014 to €873m. It reports that €780m was invested in critical infrastructure during the year.

The ESB saw a €94m increase in the value of its 50% share in the SIRO joint venture with Vodafone and the disposal of its €38m shareholding in Spanish power plant Bizkaia Energia SL.

Chief Executive Pat O'Doherty commented on the results, saying: "In the face of intensifying competition, these results reflect a solid performance across the ESB Group.

"ESB continues to focus on delivering value for our customers, shareholders and the wider Irish economy, and this is enabled by maintaining a strong financial position."