Gas and electricity bills for the most vulnerable households in Britain are predicted to soar to an average of ￡500 a month in January, stoking the cost of living crisis and increasing the pressure on the government to act to save millions of families from energy poverty.

The warning from consultancy BFY Group came as it forecast that the UK’s energy price cap could rise to an average of ￡3,840 in January following the latest surge in gas prices after Russia made further cuts in gas supplies to Europe.

Gemma Berwick at BFY said all households would need to brace for sharply higher bills and that additional government intervention was now essential to help the most vulnerable families who tend to be among the 4mn households in Britain who use prepayment meters.