Energy giant SSE increased profits to more than £370 million in the first half of this year, despite an operating loss from the part of the business which sells power to consumers.

SSE's energy supply business reported an operating loss of £16.9 million, with company bosses saying this was a result of the competitive energy market and a sustained period of warm weather.

This however is lower than the loss in 2013 when rising costs had forced SSE to increase household energy prices - which it has pledged not to do for this financial year and into next.

Operating profits in its wholesale business fell by a massive 83.4% to £26.7 million, as a result of lower electricity output from renewable sources due to the milder weather, and lower profitability in gas production - which slumped by 80.7% to £13.3 million.

Overall preliminary results for the six months to the end of September showed that the adjusted profit before tax rose by 4.6% to £370.3 million.

The power firm also reported total capital expenditure and investment of £679.3 million in Britain and Ireland, saying this work would help ensure customers have a secure and affordable supply of energy in future years.

Major investment by SSE also saw the operating profit for electricity transmission rise by 46.3% to £98.9 million.

SSE's capital investment and expenditure for 2014/15 is now forecast to total just under £1.6 billion gross over the year.

Chief executive Alistair Phillips-Davies said: "In tough market conditions we have been able to deliver solid business results at the same time as being a responsible company that does the right thing by its employees and its customers."

The company also announced that Lord Smith of Kelvin is to step down from its board on January 1 next year after 13 years of service.

The business disclosed it has lost a further 100,000 customers since June, which adds up to a loss of more than half a million accounts in the past year.

It puts this drain of customers down to increased competition between large suppliers and new entrants in the industry. SSE now has 8.89 million gas and electricity customer accounts.

Britain's energy suppliers have come under intense political pressure for raising prices in austere times even when wholesale prices have fallen.

This pressure led to SSE's pledge not to raise customer prices until 2016.

However, in June the Competition and Markets Authority watchdog announced a wide-ranging probe into the energy market to see if customers are being unfairly treated as a result of price increases by the UK's dominant big six energy suppliers.

The probe could ultimately lead to the break up of some of the country's largest energy providers.

SSE said it continued to press for more energy levies to be moved into general taxation, making bills cheaper and helping those less able to pay.

It said: "SSE would like to extend its price freeze beyond 2016, or even cut prices if further costs can be taken out of energy supply, and will work with any political party or stakeholder to find such solutions.

"It believes further savings for consumers worth around £100 - forecast to rise to around £200 by 2020 - could be made with political action to end the practice of levying policy costs on energy bills.

"Recouping the cost through energy bills takes no account of an individual's ability to pay and is therefore socially regressive."