Npower and Scottish Power are the last of the big six energy suppliers to increase prices this year, taking the average household bill to almost £1,500 a year - that is a 40 per cent increase on last year.

The latest price increases will be a major blow for the 5.5 million British households expected to experience fuel poverty this year - where more than one tenth of a household's income goes on energy bills.

For millions of vulnerable consumers, particularly the elderly and low-income families, the stark reality will mean huddling in a cold house that they cannot afford to heat this winter.

The latest prices rises came on the same day that a coalition of charities urged the Government to force energy suppliers to use more of their profits to help their most vulnerable customers. Scottish Power made £678 million profit in 2007, but spent only £2.8 million on social assistance schemes.

However, consumers do not have to wait for the Government to act as there are a number of things that can be done to keep bills to a minimum. Internet price comparison services, such as moneysupermarket.com and uswitch.com, can help consumers discover find out how much they could save by switching to a new supplier.

The cheapest tariffs are usually online accounts, where consumers manage their own meter readings and payments via the internet. The average bill on a standard Scottish power tariff will now be £1,379, but this could be reduced to £1,140 for an online deal. Many companies offer a duel-fuel discount if gas and electricity come from the same supplier.

For households with someone aged 60 to 79, a tax-free winter fuel payment of £250 may be claimed, rising to £400 for those aged 80 or more. It should be paid automatically if you receive a state pension - if you do not receive it, claim immediately.

Those living in fuel poverty may be eligible to be placed on a supplier's social tariff, designed to offer the most vulnerable households the cheapest deals but not always widely advertised.

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