English hospitals have increased emergency fuel supplies and put staff on standby to postpone operations and switch off X-ray scanners amid heightened concerns over energy provision this winter.

NHS hospital trusts across England have put their power plans under the microscope as they look to protect patients from potential outages for lifesaving equipment.

Responses to freedom of information requests to 63 NHS trusts revealed that 41 are re-examining their plans for a loss of power for this winter. A further 10 trusts said they conducted routine reviews of their business continuity plans this year, while 12 had not revised their strategies.

Concerns over the combination of a cold snap and a sudden cut-off in Russian gas supplies this winter have led ministers to examine power winter power supplies.

National Grid warned in October that, in extreme circumstances, it would be forced to enact planned three-hour power cuts with a days’ notice.

Major hospitals are exempt from this system, called rota disconnection, however businesses and the government have studied their plans for a complete power failure on the network.

The Guardian revealed last month that Whitehall officials had “war gamed” emergency plans to cope with extended energy blackouts. Documents marked “official sensitive”, which warn that in a “reasonable worst-case scenario” all sectors including transport, food and water supply, communications and energy could be “severely disrupted” for up to a week.

Despite the pressure on the NHS budgets, the responses show that most hospitals have up-to-date plans and backup generators to ensure lives are not lost due to lack of power.

A quarter of hospital trusts said they were able to run indefinitely on backup diesel generator power, providing they had access to fuel supplies. Just over 10% said they could run on backup power for 10 days.

St George’s University Hospitals, which serves 3.5 million people in south London, said its backup generators had eight to 12 hours of supply and it was in the “process of obtaining an additional contract for emergency oil supply”.

The Royal Marsden, which has hospitals in London and Surrey, said its generators could run constantly and it is keeping a higher levels of fuel in existing tanks. Frimley Health, also in Surrey, has also increased fuel volumes.

Ashford and St Peter’s Hospitals in Surrey said it had brought in additional fuel suppliers, bought spare electrical parts in case of failure, developed “more detailed action cards”, and acquired other equipment for this winter.

University Hospitals of Morecambe Bay, in north-west England, said that, in the event of planned power cuts, it would consider the “introduction of a shift system to align staff to the outage times”.

Maidstone and Tunbridge Wells NHS Trust in Kent said that, in the event of a loss of power, it would advise theatres and other specialists to “consider if they carry out essential procedures only”.

The Royal Wolverhampton said if there were warnings of outages, staff would be advised to reduce or stop non-essential services. It added that some high-powered scanners and a linear accelerator used for cancer treatment, were not protected with essential power.

University Hospitals of Leicester NHS Trust plans to tell staff not to use kettles and microwaves during maintenance of key equipment, including defibrillators, to prevent unexpected power surges.

The revised power plans come before what is expected to be another gruelling winter for NHS staff. The NHS will grind to a halt on 20 December under plans being discussed for a coordinated Christmas strike in England and Wales by nurses, ambulance workers and hospital staff.

Energy companies have also been urged to protect at-risk consumers, including those on dialysis, from being cut off.

National energy blackouts this winter would put more than 1.6 million people at heightened risk of a serious injury in their own home because of the poor quality of their property, an analysis from the Centre for Ageing Better reveals.

Holly Holder, the deputy director for homes at the Centre for Ageing Better, said: “We are calling for the rollout of a national retrofit programme to make homes warmer, safer and more energy efficient.”