A coal-fired power station is to close within a year amid rising costs in a move described as "devastating" for workers.
Energy giant SSE said that after a review it had taken the "difficult decision" to close its Ferrybridge plant in West Yorkshire by March next year.
The company said costs at the 48-year-old power station have been rising due to its age and it is forecast to lose £100 million over the next five years.
This, combined with the impact of environmental legislation and the political consensus that coal has a limited role in the future, make it unsustainable, said SSE.
Paul Smith, SSE managing director of generation, said: "This was a very difficult decision to take because of the impact on our Ferrybridge employees, their families and the community.
"It's been known for many years that the UK would have to phase out coal as it moves towards a more sustainable energy mix. We've sought to protect jobs and invest in the site to keep it running for as long as we possibly could but ultimately we've had to make this regrettable decision today."
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Mr Smith said: "Our team at Ferrybridge is highly skilled, dedicated, with a strong track record of performance, and we're keen to ensure, where possible, that staff are redeployed across other parts of the SSE group, for example at the nearby Keadby power station, or across the wider business.
"We appreciate it is a concerning time for our employees and our priority is to support them over the coming weeks and months and ensure they have a range of options available to them for the future."
Phil Whitehurst, national officer of the GMB union, said: "This is devastating news for Ferrybridge workers at a station that has years of life left to supply electricity at a fraction of the price of other energy suppliers.
"As things stand the only thing consumers will get from some of these suppliers are higher bills. Unlike Ferrybridge none of the components and little of the labour will be sourced from the UK."
SSE said it was committed to the Ferrybridge site, with a £300 million multi-fuel plant next to the power station due to open before the end of the year. The company has also submitted plans to build another multi-fuel station at the site.
The power station has been operational since 1966 and has two units, which are nearly 50 years old.
Unit 3 is undergoing routine servicing and maintenance and will return to service in August following completion of the planned outage which began in April.
Unit 4 was badly damaged in a serious fire at the site last year and SSE has been pursuing options to reinstate the equipment, but this activity will now stop, although the work to demolish the damaged equipment will continue.
Unit 4 will therefore be removed from service with immediate effect.
The announcement is another blow to the coal industry.
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