THE market share held by the Big Six energy firms has hit a record low as more consumers switched to smaller operators.

One in five consumers now hold accounts with small and medium suppliers after a mass exodus last year.

Around 5.1 electricity customers and 4.1 million gas users switched in search of better tariffs, with more than one third of these moving from a Big Six business to a challenger rival.

As of December, the UK’s giants – which include Scottish Power, SSE, nPower, British Gas and EDF – had a 79 per cent share of the electricity market, with the gas share measuring 78 per cent.

This compares with 84 per cent for both forms of power just one year previously.

In contrast, small and medium suppliers have seen their customer base grow from around five per cent for each to 21 per cent for electricity and 22 per cent for gas over four years.

The figures were released by regulator Ofgem yesterday, which warned that those who never or rarely switch are “still being overcharged”.

This is despite efforts to simplify the switching process and impose a price cap on the most vulnerable consumers.

Dermot Nolan, Ofgem chief executive, said: “The largest suppliers are under pressure as more consumers switch away to small and medium sized suppliers.

“With more customers voting with their feet, the message is clear: suppliers need to look at what they are offering to their customers or risk losing them.

“Nevertheless, there are still too many consumers who are paying too much for their energy, which is why we are introducing price protection whilst we reform the market, to make competition work for all consumers,” he added.