* Gas market oversupplied by 18 mcm/day
* Peak wind power output to hit 6 GW on Monday
LONDON, April 11 (Reuters) - British prompt gas prices fell on Monday as forecasts for high wind power output curbed demand and gas imports from continental Europe and liquefied natural gas (LNG) supplies remained strong.
Gas for instant delivery fell by 0.7 pence per therm to 26.75 p/therm by 0835 GMT, while the day-ahead contract fell by 0.58 pence to 27 p/therm.
With (Other OTC: WWTH - news) gas supply flows at about 254.3 million cubic metres (mcm) and demand expected to be about 236.3 mcm, Britain's gas system was 18 mcm oversupplied, National Grid (LSE: NG.L - news) data showed.
"We have strong wind and warmer temperatures. LNG has ramped up send out and Langeled is still flowing above usual summer levels," said Wayne Bryan, senior analyst at consultancy Alfa Energy.
Imports of gas from Norway through the Langeled pipeline were over 50 mcm/day on Monday, National Grid data showed.
Peak wind power output is expected to reach 6.1 gigawatts (GW)on Monday and 5 GW on Tuesday, the data showed.
Strong output from the country's wind farms can curb demand for electricity generation from gas plants.
Further along the curve traders said weak oil prices weighed on the gas market.
The British winter 2016 gas contract fell 0.35 pence to 32.45 p/therm, while the Summer 17 contract slipped 0.15 to 29.55 p/therm.
Brent crude prices fell below $42 a barrel on Monday as analysts cautioned a planned meeting of oil producers would be unlikely to result in a curb in global oversupply.
In the Dutch gas market, day-ahead prices at the TTF hub fell 0.05 euros to 11.15 euros per megawatt-hour.
In the European carbon market, front-year allowances edged up 0.03 euros to 5.45 euros a tonne. (Reporting by Susanna Twidale; Editing by Keith Weir)