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UK GAS-Prices rise on lower UK deliveries, higher oil

* Within-day gas up 0.65 pence to 34.80 p/therm

* Deliveries to UKCS terminals declines

* Dutch gov't agency advises production cut at Groningen

June 22 (Reuters) - British prompt gas prices rose on Wednesday morning as deliveries to UK domestic gas terminals fell due to outages, oil prices rose and a day ahead of a vote on EU membership.

Gas for within-day delivery was up 0.65 pence at 34.80 pence per therm at 0723 GMT from the previous settlement, while the day-ahead contract rose by 0.55 pence to 34.70 pence per therm.

Deliveries to UK Continental Shelf terminals have declined because the CATS terminal and pipeline and ConocoPhillips (NYSE: COP - news) ' J-Area fields are undergoing maintenance.

There is also an outage at Total (LSE: 524773.L - news) 's St Fergus gas terminal which will reduce flows for two days by 10-13 mcm/day and by 8.6 mcm/day for five days.

Despite this, the system was oversupplied by around 9 million cubic metres (mcm), National Grid (LSE: NG.L - news) data showed.

Flows from Norway through the Langeled pipeline are at 32 mcm, in line with avergae flows yesterday. Norway's Kollsnes gas plant will undergo maintenance from June 25 to July 9 which will reduce Norwegian production capacity by 38.5 mcm/day.

"We expect little to no impact on Norwegian production and have accounted for a small reduction in Langeled flows (-5 mcm/d) during that maintenance," said Cecile Langevin, Thomson Reuters gas analyst.

Oil prices rose on Wednesday above $50 a barrel after data from the American Petroleum Institute (API (Stuttgart: 565969.SG - news) ) showed a larger than expected draw on stocks.

Britain is also due to vote in a referedum on EU membership on Thursday. If the result is to remain in the EU, the pound will likely rise against the euro which would be bearish for British gas prices.

In the Netherlands' gas market, the July contract at the TTF hub was 0.52 euro higher at 15.27 euros per megawatt hour.

The Netherlands' National Mines Inspectorate has advised the government to cut production at the country's large Groningen gas field this autumn, local media reported on Wednesday.

The Cabinet is expected to announce its production plans for the field for the period after Oct (HKSE: 3366-OL.HK - news) . 1, 2016 on Friday, after several cuts in the past year have left it at the rate of 27 bcm on an annualized basis.

In Europe's carbon market, the front-year EU allowance price inched up by 0.05 euro to 5.61 euros per tonne. (Reporting by Nina Chestney)