* Flows through Bacton Seal at zero
* Gas market 31.5 mcm undersupplied
LONDON, Sept 6 (Reuters) - British gas prices for within-day delivery edged higher on Tuesday morning, as outages curbed domestic gas supplies, while curve gas prices slipped due to weaker oil.
Gas for immediate delivery was up 0.15 pence at 28.40 pence per therm at 0915 GMT.
Flows through the Bacton Seal gas terminal were at zero due to an unplanned outage which began at the weekend.
Meanwhile, gas supplies from the Theddlethorpe terminal were also at zero due to planned maintenance, scheduled to end on Sept. 16.
Further out on the curve gas prices were dragged lower by weak oil prices, traders said.
The Winter 2016 contract fell 0.35p to 38.65 p/therm. The Summer 2017 contract dipped 0.15p to 35.95 p/therm.
Oil prices fell towards $47 a barrel as hopes receded that imminent action would be taken to tackle a supply glut.
In the Netherlands, the day-ahead gas price at the TTF hub fell 0.47 euro to 11.63 euros per megawatt-hour.
In Europe's carbon market, front-year allowances rose 0.11 euro to 4.04 euros per tonne. (Reporting by Susanna Twidale; Editing by Mark Potter)