The day-ahead contract was 1.25 pence lower at 9.25 pence per therm at 0855 GMT.
The within-day contract dropped by 1.50 p to 9.75 p per therm.
UK gas-for-power demand is expected to fall on Friday when wind generation is forecast to ramp up.
Peak wind generation is forecast to soar to 13.7 gigawatts (GW) on Friday from 5.7 GW on Thursday, Elexon data showed.
Gas-for-power demand is expected at 7 mcm on Friday, compared to 32 mcm on Thursday, Refintiv data showed.
The system was undersupplied by 4.8 million cubic metres (mcm) with demand forecast at 177.1 mcm and flows at 172.3 mcm/day, National Grid data shows.
"The UK gas balance has reached a deadlock for the summer," consultancy Wood Mackenzie said.
It added that as the lockdown is placing huge pressure on electricity and fuel markets and UK gas demand will be weak throughout the summer.
"We expect that demand will come in 18pc below its five-year average," said Hadrien Collineau, senior analyst at Wood Mackenzie.
In the Dutch gas market, day-ahead gas price at the TTF hub dropped by 0.40 euro to 3.55 euros per megawatt hour.