Energy provider npower has been criticised for too readily cutting customers off and not helping those in debt.
Regulator Ofgem has hit out at npower as being the supplier with "most work to do in improving the way it helps customers who risk falling into debt with their energy bills".
Overall providers' disconnection rates have fallen from 17,000 in 2003 to 5,000 in 2006.
However, npower cut off 70 gas customers per 100,000 for non-payment of bills in 2006 around double the number cut off by EDF. Scottish Power, Scottish and Southern Energy and E.On all cut off less than 25 customers per 100,000.
By the end of 2006, five per cent of electricity and four per cent of gas customers were repaying a energy debt.
The number of people having prepayment meters for gas and electricity because of energy debts also rose in 2006.
The regulator is now calling on npower in particular to improve how it deals with customers falling behind with bills especially as energy prices rise.
Ofgem chief executive Alistair Buchanan said: "At a time when some energy suppliers have announced double-digit price rises it is vital suppliers ensure they are offering the best support to people in debt or danger of falling into debt.
"This is why npower must do more to match the best practice set by the leaders in this field."
However, he added there was "no grounds for complacency" from other suppliers.
Npower meanwhile has refuted the claims from the watchdog.
"We feel it is vital to professionally manage cases where people can pay but won't. We do not believe that those who pay should subsidise those who refuse to," the firm said in a statement.
"For those who are struggling, we offer a whole range of practical solutions. Our First Step Programme offers debt relief, one-to-one account management, energy efficiency advice and measures plus benefit entitlement checks."
It added: "It is wrong to conclude a higher number of disconnections is due to poor processes.
"Indeed, we are confident our disconnection processes are robust - a supply disconnection is only ever carried out as a last resort after a painstaking 14 step process and multiple attempts made to resolve the issue with the customer.
"The report does not provide any evidence that we have been disconnecting inappropriately."
The firm added its disconnection numbers would fall by 20 per cent through a new project to fit more gas prepayment meters as an alternative to disconnection.