Britain's bitterly cold winter boosted the profits of British Gas owner Centrica after the company raised tariffs by 6% in December.
The rise in profits, from £345 million in the same period last year, is likely to spark anger despite the company pledging to halt further tariff hikes.
Campaigners have called for the company to go further and cut prices.
Centrica chief executive Sam Laidlaw said: "With our customers using more gas to stay warm during the unusually cold winter, we're doing everything we can to help them keep their energy costs under control and make bills simpler and clearer."
More top news
A British man was grounded in Bermuda as his new wife continued to Cuba without him after drunkenly threatening the flight crew.
A petition calling for Tony Blair's anti-poverty award to be taken back has gained more than 90,000 signatures.
American scientist, who was the co-discoverer of DNA, is offering his Nobel Prize medal at auction and it could sell for up to $3.5 million.