LONDON - Britain's National Grid asked coal-fired power plants to be warmed up as a back-up option for power generation on Thursday as cold weather was expected to push up demand.

"The ESO has issued a notification that we will warm winter contingency coal units for potential use on Thursday 26 January," National Grid Electricity System Operator said on Twitter.

"This notification is not confirmation that these units will be used on Thursday, but that they will be available to the ESO, if required."

National Grid requested three coal-powered generators to be fired up on Sunday, but stood them down a day later as the supply picture had improved. It also activated a scheme through which it offered to pay customers to use less power.

(Reporting by Muvija M)