By Susanna Twidale

LONDON (Reuters) -Three more British energy suppliers have ceased to trade, regulator Ofgem said on Wednesday, leaving more than 230,000 customers potentially facing the prospect of higher bills.

The failure of Enstroga, Igloo Energy and Symbio Energy has taken the tally of British energy suppliers to go bust this month to nine as wholesale energy prices have hit records.

The price for households of the most widely-used energy tariffs are capped in Britain meaning some smaller firms, with less capital to hedge customer needs on the wholesale market have struggled to keep pace with costs.

Igloo, the largest of the latest suppliers to cease trading, with 179,000 customers, said the price cap had made its business unsustainable.

“The basis on which it’s (the cap) calculated by Ofgem is designed to favour the largest suppliers and any calls to review this by the challenger brands, like Igloo, continue to be resisted,” Igloo said in a notice to its customers.

The price cap is reviewed twice a year using a formula made up of costs such as wholesale energy prices and environmental and social levies.

The cap will rise by 12%-13% from Oct. 1 but wholesale prices have risen significantly since that announcement was made in August.

Ofgem said any customers’ outstanding credit would be protected and a new supplier would be found.

Customers’ potential new energy costs will be covered by the energy cap but if they were on cheaper fixed tariffs they may have to pay more with their new supplier.

(Reporting By Susanna Twidale, additional reporting by Nigel Hunt; Editing by Kirsten Donovan and Barbara Lewis)