Just three in five of the poorest people in Brighton and Hove are topping up their gas and electricity pre-payment meters using vouchers sent out under a government scheme.
But almost 11,000 vouchers sent out to homes in Brighton and Hove in October, November and December have not been used, according to the Department for Energy Security and Net Zero.
Out of 27,590 homes with a pre-payment meter in Brighton and Hove, some 16,740 or about 61 per cent had been used.
The numbers suggest that a higher proportion of people in Brighton and Hove are missing out on the help compared with almost every other part of the country.
The figures emerged as the Energy Security Secretary Grant Shapps pushed suppliers to do more to help support vulnerable customers.
Homes across Great Britain were promised £400 in payments this winter to help them with energy bills.
For most customers the money is automatically deducted from their energy bills. But those who have a pre-payment meter have to redeem vouchers – and the take-up was low in earlier months.
In the final three months of last year – the first three months of the scheme – 359,630 deductions were made from 366,200 fuel bills.
The government said that a record level of energy bill support reached vulnerable households last month.
But many were missing out, notably those with pre-payment meters. Across the country, they used 1.7 million vouchers last month – more than in previous months – and three quarters of all vouchers were now redeemed, the government said.
But it added that take up was low in earlier months among those who paid their energy bills through a pre-payment meter and had to redeem their vouchers.
The fewest households making use of the support were in London where over a third of vouchers remain unclaimed, the government said.
Along with Brighton and Hove, redemption rates for the vouchers were also low in Glasgow and Edinburgh.
Mr Shapps said: “The help we’ve put in place means we are covering around half of most households’ energy bill this winter – this is an unprecedented level of support.
“With January temperatures having dropped to as low as -10C in some parts of the country, I am pleased to announce today a record numbers of households taking up the government support.
“But many households are yet to redeem the vouchers they are entitled to and I want energy companies to redouble their efforts to get the support to those who need it.”