Ofgem is looking at whether people are losing hundreds of pounds a year because they have no way of buying cheap energy deals online.

Around a quarter of households are not connected to the internet, with older people disproportionately affected by not being online.

Andrew Wright, a senior director at Ofgem, said energy companies had a duty to treat customers equally.

“Arguably, those who don’t have access to online tariffs may well be being discriminated against,” he told a panel of MPs. “We are considering this in at the moment relation to a number of companies though we’re not yet at the stage of active investigation.”

Research by Age UK showed in 2008 that pensioners are the least likely to use the internet to switch energy supplier, with only 16 per cent shopping around for the best deals.

Michelle Mitchell, charity director at Age UK said last night: “Many older customers are unable to access cheaper bills by switching energy suppliers online."

There are more than 11 million people of pension age in Britain, meaning a huge number of older energy customers may be losing out.

SSE, the owner of Southern Electric, is one of the only energy companies to offer its customers the same deals online and offline.

Ian Marchant, the chief executive of SSE, estimates that providing energy through online billing only saves a company £10 to £20 per customer, but some suppliers offer discounts of up to £200 for buying online.

This means that in many cases offline customers are heavily subsidising online customers.

Ofgem said energy companies can still try to attract new customers with bargain offers, but they do have to be careful about making sure everyone has access to the same deals.

“There are clear rules about how they should be doing it,” Mr Wright said. “It should be very transparent and for a fixed period. We’re not always convinced the offers that are out there adhere to that. On some of these, it’s not obvious why [the deals] are restricted to online. You don’t receive an email and you don’t have an online service. You just acquire online.”

Ofgem is currently working on reforms for energy tariffs to make them simpler.

Energy UK, which represents the 'Big Six' energy companies, declined an immediate request for comment.

Article from the Daily Telegraph