THE boss of an energy firm employing 3,000 North-East workers is reportedly facing the sack days after the company revealed a two-thirds slump in half-year profits.

Paul Massara, who has led the firm since January 2013, will be moved aside in favour of chief operating officer Paul Coffey, but the under-fire gas and electricity company has declined to confirm the speculation.

It added: "We are currently reviewing the details of a plan to improve npower's performance and will communicate more details about that plan in due course."

The energy supplier has been plagued by problems with its billing system, which have contributed to a customer exodus. Last week, it said it had lost 300,000 customer accounts over the last year.

Npower said last week that first half profits had fallen 65 per cent to £38m.

The firm, which has 5.1 million gas and electricity customer accounts, lost 300,000 customers after a revamp of its billing system 18 months ago led to errors that saw some households receive multiple bills while others received none.

It also said households had used less energy in the period compared to a year ago.

Mr Massara has previously written to all customers apologising for the billing problems and pledging that no-one would be left out of pocket as a result of billing failures.

But last month watchdog Ofgem ordered npower to give free energy to customers whose previous energy ombudsman rulings in their favour had been left outstanding for more than 28 days until the firm had fully resolved outstanding issues.

Mr Massara used last week's update to voice opposition to proposals on capped customer tariffs raised by the Competition and Markets Authority (CMA) last month.

The proposals came after the CMA found British households were overpaying for their energy by about £1.2 billion because they were failing to switch to get the best deals.

The cap could mean prices cut or frozen for about 70 per cent of customers with the Big Six providers, which also include British Gas, SSE, EDF Energy, E.ON and Scottish Power.

But Mr Massara said the company did not support the idea.

Last year, Npower's office in Thornaby, near Stockton was closed as part of a drive to cut costs and make its Rainton Bridge offices in Houghton le Spring, where it employs about 3,000 people, the centre of npower customer service operations. Npower has also shifted back office work overseas to India and also to outsourcing companies in the UK.