* Day-ahead gas was up 1.10 pence at 67.50 pence per therm at 0923 GMT.

* Within-day gas price up 0.50 pence at 67.50 p/therm.

* Gas prices rose due to low temperatures, which increased demand, and as wind power production was at very low levels, a trader said.

* Average daily temperatures in Britain are expected to be 3.9 degrees Celsius on Monday, colder than previously seen, rising to 5.4 C on Tuesday.

* Power from renewable sources was scarce. Peak wind generation is forecast at 1.7 gigawatts (GW) on Monday, from a total capacity of more than 12 GW, and is expected to rise to 3.4 GW on Tuesday.

* Low output from wind turbines typically increases demand for electricity generated in gas-fired power stations.

* The system was undersupplied. Gas demand in Britain was forecast at 292.4 million cubic metres/day and flows at 283.1 mcm/day, National Grid data showed.

* Norwegian gas flows to Britain rose to 127 mcm/day, from 123 mcm/day on Friday.

* Two vessels with liquefied natural gas are expected to arrive in Britain on Monday and two more by the end of the week. .

* Jan contract fell 0.20 p to 68.50 p/therm.

* Day-ahead Dutch gas at the TTF hub rose by 0.07 euro to 24.55 euros per megawatt hour.

* The benchmark Dec-19 EU carbon contract rose by 0.12 euro to 25.04 euros a tonne.