Rising energy bills are a concern for many

About a million consumers use pre-payment meters, which need to be reset each time there is a price move.

There is often a time-lag between the price rise and meter reset, which means customers can be hit with a large bill.

Consumer groups have welcomed the move to scrap backdating, saying it removes a "blight" from the lives of many low-income energy users.

Rough deal

British Gas has recognised that backdating price rises has a devastating effect on poor households Teresa Perchard, Citizens Advice

Pre-payment customers have long been seen as getting a rough deal from energy providers.

Despite paying in advance for their energy, they fork out on average �45 more a year than standard quarterly bill payers.

Pre-payment customers pay on average a �100 more a year than direct debit payers.

Many of those with pre-payment meters are on low incomes and can least afford to pay more for their energy.

In particular, the practice of backdating price rises has drawn fire from consumer groups and charities.

They have argued that it can lead to low income consumers being hit with unexpectedly high one-off bills.

"British Gas has recognised that backdating price rises has a devastating effect on poor households," Teresa Perchard, Citizens Advice spokeswoman said.

"Pre-payment meter customers already get a raw deal, and our evidence shows that some of the most vulnerable customers are ending up owing hundreds of pounds, exacerbating the hardship they face," Ms Perchard added.

Citizens Advice and Energywatch called on other providers, including Powergen, Scottish Power and NPower, to abandon backdating.

Recently, an early day motion was signed by 79 MPs urging an end to the practice.

British Gas said that it had decided to scrap backdating after "listening to its customers".