Iain Conn, the Centrica chief executive, said that loss-leading deals would no lomger be offered

Centrica has blamed the government’s looming energy price cap after announcing 4,000 job cuts despite bumper profit margins at British Gas.

Britain’s biggest energy supplier also revealed plans to persuade more than a million of its customers to switch to fixed tariffs that will not be covered by the cap, potentially locking them into paying higher prices.

The government is legislating to cap all standard tariffs, cutting bills and squeezing suppliers’ profits, after competition authorities found that customers were paying hundreds of pounds a year too much for their energy.

British Gas supplies gas and electricity to 7.8 million households in the UK, with 4.3 million on its standard tariff. Centrica reported yesterday that British Gas’s household supply profits rose to more than £566 million