Hargreaves Services, which owns the rump of Scotland’s coal mining industry, saw operating profit fall by 86per cent last year to £5.2million.

The accelerated closure of coal-fired power stations drove writedowns of £12.4m, with coal and coke sales plummeting from seven million to under two million tonnes in two years, turning a £49m profit for the business into a £400,000 loss.

Hargreaves said last month that the fall in the pound would provide some relief. But it expects to be producing coal from just one site in Scotland by the end of the summer, with six other sites in wind-down, as it is now impossible to produce power station coal at a profit. Thermal coal prices have dropped from around $180 a tonne in 2008 to about $50.

The group bought seven sites in Scotland from administrators of ATH and Scottish Coal in 2013. The surviving House of Water site in Ayrshire has switched to producing specialist coal for the industrial and domestic market.

The group said: “The reductions in gas prices and the increases in UK carbon taxes have significantly reduced electricity generation from coal and have precipitated the announcement of the early closure or changes to operating regimes that will significantly reduce coal usage.

"Stations closed or otherwise likely to be burning less coal include Longannet, Rugeley, Fiddlers Ferry, Eggborough and Ferrybridge. A strengthening of government sentiment against coal fired generation increases the probability of further closures.”

Meanwhile Hargreaves has set “aggressive” new business targets for its industrial services operations.

Over the next five to seven year the company is hopeful of generating between £35m and £50m of value from its property and energy project portfolio, as it continues to reduce its focus on thermal coal.

The group was reporting a drop in continuing revenue to £341m from £662m the previous year.

Chairman David Morgan said: “After two challenging years, we have a clear opportunity in front of us to develop and deliver significant shareholder value.

“Our portfolio of property and energy projects offer an exciting platform for significant value creation that is incremental to that created from our distribution and services operations.”

He added: “The £60m of legacy assets that we aim to convert to cash will strengthen a balance sheet that is already strong and allow consideration of a wide range of options to return value or capital to shareholders.”

Hargreaves has been through a radical restructuring and repositioning programme that has included a “significant” number of redundancies, which is now“fundamentally complete”.

The group said last month that the uncertainty associated with Brexit presented potential risks for its earthworks and logistics businesses, which had a significant exposure to construction activity and capital investment projects. But there was also “potential upside from government-sponsored public sector works to reflate the economy”, and the medium-term impacts were not yet clear.

The shares fell 3.25p to 190p.