Demand for gas in the UK has hit record levels over the past week
National Grid has issued its latest "balancing alert" on gas supplies.
It is the fourth warning of a potential shortfall in supplies since the current cold spell began.
These alerts are a signal to the market to increase gas supplies, and encourage electricity providers to use alternative fuels such as coal.
"When the system is running at peak demand, and supplies drop off... we issue this as a signal to the market, and ask it to respond," the Grid said.
GAS TERMS EXPLAINED
Gas balancing alert
A gas balancing alert is put out by the National Grid when expected demand is predicted to outstrip expected supply
It asks the market to react by selling more gas into the system so households do not lose power supplies
It comes as low temperatures in the UK continued to drive demand, and as outages at Norwegian gas facilities continue.
"Following notified supply losses amounting to greater than 25 mcmd [million cubic metres a day], National Grid has declared a Gas Balancing Alert," said British Gas.
The National Grid said a further gas balancing alert for Tuesday was currently under review.
Unusually cold weather has hit big Norwegian gas field Ormen Lange and a major gas processing centre, hitting North Sea gas flows from Norway at a time of increased consumption.
Monday's balancing alert from National Grid is the fourth warning issued so far this year and only the fifth since the system was introduced four years ago