LONDON, Jan 22 (Reuters) - Britain's National Grid said on Sunday it had asked for three coal-powered generators to be warmed up in case they are needed as the country faces a snap of cold weather.

"This notification is not confirmation that these units will be used on Monday, but that they will be available to the ESO (Electricity System Operator), if required," National Grid said.

Coal-powered generators were last put on stand-by in December when temperatures dropped and demand for energy rose, but they were not needed on that occasion. (Reporting by William Schomberg Editing by Tomasz Janowski)