British Gas half-year earnings at its household supply arm have fallen as it took a £50 million hit from slumping energy demand due to warmer weather.

The Centrica-owned group said underlying earnings for the residential energy supply business dropped to £133 million in the six months to June 30, down from £156 million a year earlier.

Warmer-than-normal weather, as well as lower energy prices, knocked the result at the supply business as households turned down their central heating thermostats.

The group said the division suffered a £50 million blow to earnings due to “unseasonably warm weather conditions across the UK and Europe, with April being the third warmest on record”.

But it said it halted the number of customers leaving British Gas, with a 1% rise in households supplied to 7.5 million as at the end of last month.

The wider Centrica business reported underlying earnings of £549 million, nearly half the £1.04 billion posted a year earlier.

On a reported basis, Centrica swung to an operating loss of £69 million, from £1.68 billion earnings a year ago.

Chris O’Shea, group chief executive of Centrica, said: “I’m pleased with the progress we’ve made in some areas during the first half despite a challenging backdrop.”

He added there was “still much more to do across the group”.

“That’s why we’re accelerating our efforts to make Centrica a leaner, more agile organisation, transforming the way we do business, allowing us to deliver on our full potential,” he said.

Efforts include using artificial technology (AI) to “drive customer retention and support commercial growth” as well as simplifying the group by cutting its overheads, according to the group.

The results come after Centrica earlier this week announced it was investing £1.3 billion for a 15% stake in the new Sizewell C nuclear power plant in Suffolk.