June 12 (Reuters) - British wholesale gas prices fell on Wednesday, despite the system being undersupplied, following a decline in oil prices and as strong wind power generation is expected to cover part of the country's energy demand.
* Day-ahead gas was down 0.45 pence at 28.75 pence per therm by 0726 GMT.
* Further along the curve, the July UK gas contract fell by 0.40 pence to 27.60 p/therm. The August contract also declined by 0.33 pence to 28.85 pence/therm.
* Gas prices followed a decline in oil on Wednesday and, combined with forecasts for stronger power production at Britain's wind turbines, moved lower, a gas trader said.
* Oil prices fell nearly 2%, weighed down by a weaker demand outlook and a rise in U.S. crude inventories despite growing expectations of ongoing OPEC-led supply cuts.
* Peak wind power generation is expected to be 6.8 gigawatts (GW) on Wednesday, compared with total metered capacity around 12.1 GW. Output is expected to rise to 8.0 GW on Thursday, Elexon data showed.
* Strong power production from wind turbines typically reduces demand for electricity from gas-fired power stations.
* Average daily temperatures in Britain are expected at 11.9 degrees Celsius on Wednesday and remain stable on Thursday.
* Prices fell despite a supply deficit. The UK gas system is expected to be 6.3 million cubic metres (mcm) undersupplied on Wednesday, with demand forecast at 207.1 mcm and supply at 200.8 mcm, National Grid data showed.
* Flows from Norway to Britain were expected to stay flat at 77 mcm/day, as the Vesterled pipeline remains shut.
* The Shagra is the only tanker heading to Britain at the moment and due to arrive at South Hook on June 21.
* Day-ahead gas at the Dutch TTF hub was down 0.25 euros at 10.95 euros per megawatt hour.
* The benchmark Dec-19 EU carbon contract fell by 0.24 euros to 24.74 euros a tonne. (Reporting by Lefteris Karagiannopoulos in Oslo; editing by David Evans)