UK GAS-Within-day prices rise in undersupplied market

* UK gas market 13.8 mcm undersupplied

* LNG cargos weigh on other contracts

May 17 (Reuters) - British within-day gas prices rose on Tuesday morning, as imports from Norway fell and an outage at the Bacton Seal gas terminal cut domestic supply.

Gas for within-day delivery fetched 31.00 pence per therm at 0837 GMT, up 1.00 pence from the last settlement.

With (Other OTC: WWTH - news) supply flows at about 216.4 million cubic metres (mcm)/day, and demand expected to be 230.2 mcm/day, Britain's gas system was 13.8 mcm undersupplied, National Grid (LSE: NG.L - news) data showed.

Domestic supplies of gas were cut due to an outage at Total (LSE: 524773.L - news) 's Bacton Seal gas terminal.

The outage, which began on May 16, would last two days and cut output by 9 mcm/day, the company said.

Norwegian imports through Langeled, Britain's main gas import pipeline, were around 15 mcm/day, down from around 40 mcm the previous day, National Grid data showed.

Other gas contracts were subdued due to the scheduled delivery of several cargos of liquefied natural gas (LNG), traders said.

The Al Mafyar LNG tanker arrived at South Hook on Tuesday, while three more tankers are scheduled to arrive in the country over the next six days.

Gas for day-ahead delivery slipped 0.08 pence, to 30.90 pence per therm.

The June contract fell 0.25 pence to 29.80 pence per therm, while the Winter '16 contract was down 0.20 pence at 36.65 pence per therm.

In the Netherlands' gas market, the day-ahead price at the TTF hub gained 0.08 euro to 13.18 euros per megawatt-hour.

In Europe's carbon market, the front-year EU Allowance price fell 0.06 euro to 6.05 euros per tonne. (Reporting by Susanna Twidale; editing by Jason Neely)