UK GAS-Prices rise due to tight domestic supplies

* Gas system short by 7.4 mcm

* SEGAL maintenance has limited flows to St Fergus Shell

LONDON, Aug 27 (Reuters) - Wholesale natural gas prices in Britain rose on Thursday morning due to tight supplies from the UK Continental Shelf.

Prices for next-day delivery rose by 0.20 pence to 38.55 p/therm by 0900 GMT, while gas for immediate delivery was up 0.50 pence at 38.75 p/therm.

Britain's gas system was undersupplied by 7.4 million cubic metres (mcm), with demand forecast at 196.9 mcm and flows at 189.5 mcm/day, National Grid (LSE: NG.L - news) data showed.

Supplies from the UK Continental Shelf have fallen to under 100 mcm due to maintenance at Entry SEGAL pipeline system which has limited the flow of Norwegian gas to the St Fergus Shell terminal.

This outweighed higher flows along Norway's Langeled pipeline, traders said. Flows through the SEGAL pipeline are expected to return on Friday.

Further along the curve, gas for September delivery was up 0.40 pence at 39.35 p/therm.

Prices were also slightly higher on the Dutch TTF market, with gas for day-ahead delivery up 0.08 euro at 18.98 euros per megawatt-hour.

In Europe's carbon market, benchmark EU Allowances (EUA) was down by 0.02 euros to 8.09 euros a tonne. (Reporting by Nina Chestney; editing by Jason Neely)