UK big six energy firms lost record number of customers in Sept – data

LONDON (Reuters) - Britain's big six energy firms lost a record number of customers in September to smaller challengers, data from industry group Energy UK showed.

A total of 163,274 customers switched from the Big Six, the data published this week showed, ramping up pressure on energy companies already facing the introduction of a price cap on their most common tariffs.

Britain's energy market is dominated by the so-called big six including Centrica's ,(CNA.L) British Gas, SSE (SSE), Iberdrola's (IBE.MC) Scottish Power, Innogy's npower (IGY.DE), E.ON (EONGn.DE) and EDF Energy (EDF.PA), which account for about 85 percent of the retail electricity market.

The data did not detail which companies lost the most customers.

Britain's biggest supplier, British Gas increased prices by 12.5 percent for millions of its customers in the middle of September.

"Competition between the independents and the Big Six is likely to remain fierce, even with the... price cap, as the smaller suppliers are likely to continue to offer the cheapest deals in the market," analysts at Jefferies said in a research note on Friday.

(Reporting By Susanna Twidale; Editing by Elaine Hardcastle)