Day-ahead gas was up by 0.35 pence at 27.85 p/therm at 0928 GMT.

Within-day gas edged up by 0.10 pence to 27.70 pence per therm.

The price of EU carbon permits extended gains and pushed wholesale prices up, including forward contracts which had declined in earlier trade, said a British gas trader.

"Looks like another charge to break 30 euros," he said commenting on the carbon price.

The benchmark Dec-19 EU carbon contract was up 0.41 euro at 29.60 euros a tonne, having touched a 13-year high on Tuesday.

Average daily temperatures in Britain are forecast to reach 23.8 degrees Celsius on Thursday and are seen falling to 21C on Friday.

However, the UK Met Office said a temperature of 39C could be felt in south-east England today, which would be all-time record high.

The current July record is 36.7C in 2015. The all-time UK temperature record is 38.5C in Faversham in August 2003.

Peak wind generation is expected at 6.6 gigawatts (GW), out of a total metred capacity of 12 GW, and is expected to fall to 4.2 GW on Friday.

Oversupply also eased from earlier this morning.

The system is now 3.1 million cubic metres (mcm) long, with demand forecast at 146.6 mcm and supply seen at 149.7 mcm per day, National Grid data shows. Earlier in the day, oversupply had reached 16 mcm.

Total Norwegian flows to Britain are 9 mcm higher than the previous working day at 55 mcm/day.

Britain is set to receive two LNG cargoes before the end of the month.

The August contract was trading 0.50 pence higher at 28.50 p/therm.

In the Dutch gas market, the day-ahead price at the TTF hub edged down by 0.02 euro at 10.33 euros per megawatt hour.

The August gas price at the Dutch TTF hub was up by 0.12 euros at 10.27 euros per megawatt hour.