In a report published on Tuesday, The National Audit Office (NAO) said the estimated cost of all energy subsidies compares with the government's original forecast of around 139 billion pounds.

The government rolled out a raft of support measures last year as energy costs spiked.

In the interest of speed, it chose to role out universal support, granting 400 pounds this winter to each household regardless of need. It also capped average domestic energy bills at 2,500 pounds a year until March 31 and at 3,000 pounds until April 2024.

This universal approach potentially increased the risk of fraud and error, NAO said.

"This approach led to compromises – introducing these interventions at speed meant that BEIS (The Department for Business, Energy and Industrial Strategy) has less time to consider fraud and error risks; and their universal nature meant that a significant number of households received financial support they did not need," said Gareth Davies, head of NAO.

When the scheme was first launched the government had said average bills would be capped at 2,500 pounds a year until April 2024.

A rapid drop in wholesale energy prices, which soared after Russia invaded Ukraine last year, means Britain's subsidy scheme to help households could be paying out nothing in the second half of the year, analysts said last month.

Looking ahead, the government is considering targeted schemes in an effort to reduce the overall cost, while mitigating risks of fraudulent claims and errors wherein suppliers manipulate energy use by consumers, the NAO report said.

Last month, Britain announced plans to scale back energy subsidies for businesses for the next financial year by about 85% to 5.5 billion pounds.

Without the government measures average household energy bills were set to rise more than 170% to over 3,500 pound this winter from a year earlier.

($1 = 0.8318 pounds)