LONDON, March 27-- Six British big energy suppliers will face a competition inquiry after the energy regulator Ofgem published its first competition assessment of energy market on Thursday.

The joint assessment, carried out by Ofgem, the Office of Fair Trading and the Competition and Markets Authority (CMA), identified weak competition between larger energy suppliers, low customer trust and engagement, and barriers to entry and expansion.

Ofgem was proposing a reference to the CMA to investigate the energy market to ensure that there are no further barriers to effective competition.

"It's right that there is a full investigation into whether the 'Big Six' are preventing effective competition in the UK energy market," commented by British Prime Minister David Cameron through his twitter account.

The big six -- SSE, Scottish Power, Centrica, RWE Npower, E.On and EDF Energy -- account for about 95 percent of the British energy supply market.

According to a joint assessment, 43 percent of consumers did not trust energy suppliers to be open and transparent in their dealings with them in 2013, compared to 39 percent in the previous year. Average profits for the six larger suppliers for supply and generation increased from 3 billion pounds in 2009 to 3.7 billion pounds in 2012.

Energy supplier SSE announced on Wednesday it will freeze domestic gas and electricity prices at their current levels until 2016. "This shows the Big Six are starting to realize they need to take big action if they want to keep their customers," said Edward Davey, secretary of state for energy and climate change.