Britain's electricity could be in short supply over the coming days due to a lack of windy weather, the National Grid has said.
The National Grid warned on social media that "unusually low wind output" and a number of generator outages has meant it will be operating with a reduced spare capacity.
"We’re forecasting tight margins on the #electricity system over the next few days owing to a number of factors including weather, import and export levels and availability of generators over periods of the day with higher demand," wrote Great Britain's Electricity System Operator (ESO) on Twitter.
"Unusually low wind output coinciding with a number of generator outages means the cushion of spare capacity we operate the system with has been reduced."
The National Grid added that it would be exploring measures and actions to make sure there is enough generation available to "increase our buffer of capacity".
The electricity system operator later provided a further update to say "margins are adequate" for Thursday and it is monitoring how the situation develops.
It is rare for concerns to be raised about the National Grid's electricity supply.
In 2015 the National Grid made an urgent call to the energy industry for more power as "a result of multiple plant breakdowns".
The power firm requested an additional 500 megawatts - an equivalent to the power surge experienced at half time during a big sports event.
But this was the first time in three years that the National Grid had launched an appeal for more power. A spokesman later said the additional power had been received.