British utility Centrica saw operating profit fall 35% in the first half of the year as a mild winter in Britain led to reduced energy demand and extreme weather in North America increased costs.

Centrica made £1.032bn in operating profit, down from £1.583bn a year earlier, it said today.

Revenues increased by 15% to £15.7bn.

The company was hit by £65m of costs relating to the polar vortex cold snap that hit North America earlier this year. It also posted write-offs of £40m relating to cancelled wind farm projects.

The company also entered the Irish market during the period through its €1.1bn acquisition of Bord Gáis.

Centrica said integrating this business into its wider operations was a priority for the second half of the year. 

It said it expected Bord Gáis to generate €40m in earnings before interest, tax, depreciation and amortisation during 2015.

"The first half of the year has seen challenging market conditions across the Group, both as a result of the weather and reflecting the wider political environment," said Centrica chairman Rick Haythornwaite in a results statement.