Price comparison website moneysupermarket.com has called on smaller energy companies to "come out and play with the big boys".
The call comes after supplier OVO Energy launched a new online tariff which placed it at the "top of the ladder" of cheap duel fuel deals.
At an average of £855 per year, the tariff is £44.04 cheaper than the best offering from British Gas.
Scott Byrom, the website’s utilities manager, said: "It’s great to see smaller providers putting pressure on the energy giants, especially as the two top spots are now being held by OVO Energy and First Utility.
"Despite some price cuts to select online tariffs earlier in the year the Big Six have got some ground to make up if they want to reclaim the crown of having the cheapest overall energy product in the UK."
However, the expert warned that there is still a significant gap between standard and online deals.
This could encourage elderly people, who traditionally use a larger proportion of their income on heating, to seek additional ways of raising funds.
Schemes such as equity release can provide a homeowner with cash that may be tied up in the value of their property.
