People should not try to reduce their energy bills by improvising open fires at home, fire chiefs have warned, after a man in south-west London set fire to his property by burning timber in his living room to keep warm.

The man was trying to avoid putting on the central heating in his home, fire investigators said.

Fuel poverty campaigners said the incident – one of at least 100 involving open fires, log burners and heaters in the capital in the last few months – laid bare “the harsh and dangerous reality of the cost-of-living crisis”.

Issuing an urgent safety warning, the London fire brigade (LFB) said the cause of the blaze on 26 April had been determined as “involving an open fire being used instead of gas central heating.”

It is understood to have also been caused by combustible items too close to an open fire. The London ambulance service said it treated three people at the property in New Malden, with one man being taken to hospital as a priority.

The LFB said there had been more than 100 fires involving open fires, log burners and heaters in the past few months.

It fears the rise in energy bills could result in a surge of fires as people resort to alternative means to heat their homes throughout the colder spells of the year.

Charlie Pugsley, assistant commissioner for fire safety, said: “We know this is a difficult time and people are thinking about ways to reduce their energy bills, but we’re really concerned that they may be putting lives at risk by doing so.

“If you do have a log burner or an open fire, follow our advice carefully. Almost 30% of fires involving log burners, heaters and traditional open fires are caused by items being placed too close to a heat source. Always use a fire guard and keep anything that could catch alight well away, such as logs and kindling which could be ignited by radiating heat.”

Adam Scorer, the chief executive of the fuel poverty charity National Energy Action, described the incident as a “harsh and dangerous reality of the cost-of-living crisis”.

“One in four UK households are now in fuel poverty, which means millions are facing impossible choices because of their high energy bills,” he said. “Some are choosing between heating and eating, others are self disconnecting completely and some are even starting open fires. These aren’t coping strategies. It’s people who feel they have no safe choice to make.”

A government spokesperson said: “We recognise the pressures people are facing with the cost of living, which is why we have set out a £22bn package of support, including rebates and energy bill reductions.”