UK GAS-Prices mixed due to oversupply, planned pipeline outage

LONDON, May 23 (Reuters) - The British wholesale within-day gas price fell on Wednesday due to an oversupplied system but the next-day contract rose in anticipation of planned work that will reduce flows from Norway.

* Gas for immediate delivery fell by 0.60 pence to 57.40 pence per therm (p/therm) at 0834 GMT.

* Day ahead gas rose by 0.50 pence to 58.40 p/therm.

* June gas was 1.30 pence lower at 56.90 p/therm.

* The gas system was oversupplied by almost 30 million cubic metres (mcm), with demand forecast at 174 mcm - 18 mcm lower than the seasonal average - and supply at 203 mcm, according to National Grid (LSE: NG.L - news) data.

* Flows through the Langeled pipeline, one of two key pipelines from Norway to Britain, spiked 20 mcm to 67 mcm ahead of a planned shutdown on Thursday.

* Meanwhile, the second of the two pipelines, Vesterled, is still under maintenance with start-up delayed to Thursday from Wednesday.

* "With Langeled flows off tomorrow there is a substantial supply risk whether the return of Vesterled was to be postponed again," gas analysts at Thomson Reuters (Dusseldorf: TOC.DU - news) said in a daily note.

* "Given a strongly oversupplied market and prices surging before Langeled and Kollsnes maintenance, we expect heavy injections (into storage) today and switching to withdrawals from tomorrow," the analysts said.

* Average temperatures this week will rise later this week and are set to top 17 degrees Celsius by the weekend, from 13.5 degrees Celsius on Wednesday, Thomson Reuters Eikon data shows.

* Domestic gas demand is expected to fall to 57 mcm on the weekend from 69 mcm.

* Sparse liquefied natural gas (LNG) deliveries into Britain should support prices. Rising Asian spot LNG prices (LNG-AS) this month will only make it more difficult for Britain to attract supply, which could support front-month prices.

* Britain received just two LNG cargoes this month, compared to nine cargoes in April, according to Thomson Reuters shipping data.

* Day-ahead gas at the Dutch TTF hub slipped by 0.03 euro to 22.77 euros per megawatt hour

* The benchmark Dec (Shanghai: 600875.SS - news) -18 EU carbon contract inched down by 0.01 euro to 15.94 euros a tonne (Reporting by Sabina Zawadzki; editing by Nina Chestney)