British Gas made operating profits of £585m for the first half of this year - an increase of 98%, according to data released by its parent company Centrica.
British Gas supplies gas to more than half of the UK's households and saw gas use rise by 8% and added 223,000 residential customers.
Ann Robinson, from the price comparison service, uSwitch, said that British Gas and its rival suppliers could cut prices still further.
"Today's profits suggest that suppliers could actually afford to pass on even more benefit to consumers by cutting their prices again."