* Day-ahead gas prices were up 1.25 pence at 31.50 pence per therm by 0830 GMT

* Within-day gas prices also rose 1.45 pence at 32.25 p/therm

* Traders said the rise in prices was mostly supply driven, as flows from Norway stayed at low levels as did output from wind turbines

* The system is undersupplied with demand forecast at 201.9 million cubic metres (mcm) and flows at 186.9 mcm/day, National Grid data showed

* Demand was 21.9 mcm above the seasonal norm

* Norwegian gas flows to Britain remained low, slipping to 36 mcm/day from 38 mcm/day on Friday, as flows via the Langeled and Vesterled pipelines maintained Friday's low volumes

* Peak wind power generation is forecast at 3 gigawatts (GW) and is expected to stay flat on Tuesday, National Grid data showed

* Average daily temperatures are forecast at 13.0 degrees Celsius and staying flat on Tuesday before rising to 13.5C over the weekend, Refinitiv Eikon data showed

* Britain received two LNG tankers on Sunday and expects four more to arrive by May 27

* The June contract was up 0.50 p at 30.70 p/therm

* Day-ahead gas prices at the Dutch TTF hub were down 0.09 euro at 12.98 euros per megawatt hour

* The benchmark Dec-19 EU carbon contract was down 0.05 euro at 24.95 euros per tonne