UK GAS-Prices up as pipeline system outage continues

LONDON, June 27 (Reuters) - British wholesale gas prices rose slightly on Tuesday morning due to an ongoing outage at the Entry SEGAL pipeline system, which transports Norwegian gas to Britain's St Fergus terminal. * Day-ahead gas price was 0.10 pence higher at 37.00 pence a therm. * July gas was up 0.25 pence at 37.10 p/therm. * An outage at the Entry SEGAL system is reducing volumes by 18 mcm/day on Tuesday and Wednesday. Operator Gassco has revised the length of the outage, which started last Wednesday, to 8-10 days. * "There is a risk full return (to service) is further postponed given the multiple extension of this (outage)," said Francois Flament, Thomson Reuters (Dusseldorf: TOC.DU - news) gas analyst. * The system is balanced, with demand forecast at 149.55 million cubic metres (mcm) and flows at 149.21 mcm/day, National Grid (LSE: NG.L - news) data shows. * UK Continental Shelf production is slightly higher, likely due to the gradual return of the Laggan gas field, * In the Dutch gas market, day-ahead contract on the TTF hub was 0.25 euro lower at 15.15 euros per megawatt hour. * Benchmark Dec-17 EU carbon contract inched up by 0.03 euro to 4.81 euros a tonne. * Thomson Reuters analyst view: http://emea1.apps.cp.extranet.thomsonreuters.biz/cms/?pageid=united-kingdom-gas (Reporting by Nina Chestney)