UK watchdog extends energy market probe to June 2016

(Updates with detail, comments)

Sept 21 (Reuters) - Britain's competition authority has extended the deadline for its investigation into the country's largest energy suppliers by six months to late June 2016 to consider feedback from industry and consumer groups, it said on Monday.

Six suppliers -- SSE, Scottish Power, Centrica, RWE npower, E.ON and EDF Energy -- control more than 90 percent of the market and are under intense scrutiny because of public outrage over rising energy bills.

"As the most comprehensive investigation into the energy market since privatisation, this is... an opportunity to shape the future of this market for the better. It's important that we get it right," Roger Witcomb, chairman of the energy market investigation said in a statement.

The Competition and Markets Authority (CMA) said it would aim to deliver the findings "well within" the new timeframe, with a provisional decision by January and a final decision by the end of April.

The CMA had been expected to report its findings by late December and could go as far as enforcing the break-up of energy suppliers if it finds they are breaching competition rules.

Peter Atherton, a utility analyst at investment bank Jefferies said the companies involved were likely to welcome the delay as it means the CMA is taking extra time to consider their responses.

A spokeswoman for Centrica said it supported the CMA's decision to extend the timetable.

"We will continue to engage constructively in this process," she said.

An interim update to the probe, published in February, showed most British energy customers who have not switched supplier and/or tariff have missed out on saving up to 234 pounds ($360) a year. (Reporting by Oleg Vukmanovic in Milan and Susanna Twidale in London; Editing by Keith Weir)