UK GAS-Prices down on expected LNG supply

* System undersupplied by 7.5 mcm

* South Hook to receive a new LNG cargo on Apr 29

LONDON, April 22 (Reuters) - British prompt gas prices were largely lower on Wednesday morning in anticipation of more supplies of liquefied natural gas (LNG), while gas for immediate delivery was slightly up on undersupplied system.

Gas for day-ahead delivery was down 0.15 pence to 45.85 pence per therm at 0900 GMT.

Further along the curve, gas for delivery next month was down 0.27 pence at 44.78 pence per therm.

"Prompt prices are trading sideways on the back of the tight system, though the glut of LNG due into the UK is weighing on the front month and prices into the near curve," a UK gas trader said.

South Hook LNG terminal is expected to receive another cargo on April 29, which the traders said would help to keep flows from the terminal high next week.

Meanwhile, temperatures were expected to fall towards the weekend from a maximum of around 18 degrees on Wednesday, Britain's Met Office said.

Gas for within-day delivery was up 0.05 pence at 45.80 pence per therm on an undersupplied system.

National Grid (LSE: NG.L - news) data showed supply was forecast at 197.2 million cubic metres (mcm) on Wednesday, while demand was seen at 204.7 mcm, meaning the system was undersupplied by 7.5 mcm.

In the Netherlands, the day-ahead gas price at the TTF hub was down 20 cents at 21.55 euros per megawatt-hour.

There is an ongoing maintenance affecting injections at Dutch storage facility Grijpskerk, but its duration is unknown. Any update on that could impact the Dutch day-ahead price, analysts at Thomson Reuters Point Carbon said.

Production at the Groningen gas field in the Netherlands, which supplies about 15 percent of Europe's gas needs, will not exceed 36.4 billion cubic meters (bcm) in 2015, Dutch Economy Minister Henk Kamp said on Tuesday.

In February, Kamp cut first-half 2015 production to 16.5 bcm, sending gas prices surging in Northwest Europe. The overall annual target for the year is still to be confirmed in July.

The benchmark European Union carbon price was trading 3 euro cents up at 7.15 euros a tonne on ICE Futures Europe. (Reporting by Nerijus Adomaitis; editing by Nina Chestney and Louise Heavens)