UK GAS-Prices rise on outage extensions

* Day-ahead gas up 0.55 pence at 36.35 p/therm

* Gas system very slightly undersupplied

July 25 (Reuters) - British wholesale gas prices rose on Monday morning due to the extension of some outages in Norway and Britain.

Gas for day-ahead delivery was 0.55 pence higher at 36.35 pence per therm at 0843 GMT from the previous settlement.

The gas system was very slightly undersupplied with demand forecast at 180.9 million cubic metres (mcm) and flows at 178.7 mcm/day, National Grid (LSE: NG.L - news) data showed.

An outage Norway's Heimdal field has been extended until Aug. 7 and flows through the Vesterled pipeline and the FLAGS pipeline are not expected to reach 40 mcm/day until then.

An outage at Britain's North Morecambe gas sub-terminal was also extended last week until Aug. 1 which has cut production rates to zero and the Teesside gas processing plant is also undergoing an outage which has reduced capacity by 30 percent on Monday.

Gas-for-power demand has been robust at 54 mcm/d over the past week but is forecast to drop to 40 mcm/d between now and Aug. 8 due to stronger winds and a drop in total power consumption, Thomson Reuters (Dusseldorf: TOC.DU - news) analyst Oliver Sanderson said.

Exports to continental Europe through the InterconnectorUK are also slightly higher compared to the end of last week.

Gas prices further along the curve edged higher, with the August gas contract up 0.50 pence at 36.65 p/therm.

In the Netherlands, the day-ahead price at the TTF hub rose by 0.27 euro to 14.82 euros per megawatt-hour.

There has been a sharp increase in Italian imports of gas via Switzerland due to less Russian exports, which has impacted the gas available at the TTF hub.

In Europe's carbon market, the front-year EU allowance price inched up by 0.01 euro at 4.58 euros per tonne. (Reporting by Nina Chestney)