UK GAS-Prompt prices rise as Norway outage tightens supplies

* System 22 mcm short - National Grid (LSE: NG.L - news)

* Flows from Norway to Britain drop

LONDON, Nov 26 (Reuters) - British gas prices rose on Thursday on short supplies as flows from Norway were reduced after extended maintenance at one of its fields.

Gas for within-day delivery rose 0.45 pence to 37.75 pence per therm by 0904 GMT, while gas for next-day delivery rose 0.25 pence per therm to 37.75 pence per therm.

The system was 22 million cubic metres (mcm) short, with demand forecast at 288 mcm while supply was pegged at 266 mcm, National Grid data showed.

Imports from top supplier Norway were lower after production capacity at the Kvitbejoern gas field was cut by 7.1 mcm due to an unplanned outage.

Flows via the Langeled pipeline between Norway and Britain were around 51 mcm per day, down from around 59 mcm Wednesday, Thomson Reuters Point Carbon analysts said.

"Yesterday Gassco prolonged the length of the outage to 6-7 days compared to a previously reported 36-48 hours," the analysts said.

"The prolongation of the outage means that we now expect Langeled flows to fluctuate around 51 mcm/d for the next 6 days compared to a previously expected 65 mcm/d."

The Met Office forecast temperatures of around 10 to 12 degrees on Thursday, above seasonal norms, before dropping on the weekend.

Gas prices for December rose 0.02 pence to 37.67 pence/therm.

In the Netherlands the day-ahead gas price at the TTF hub was down 0.08 euros to 17.80 euros per megawatt hour.

In Europe's carbon market the benchmark EU Allowance (EUA) edged up 0.01 euros to 8.63 euros a tonne. (Reporting by Sarah McFarlane; editing by Jason Neely)