UK GAS-Prices supported by upcoming Norwegian maintenance

* Next (Other OTC: NXGPF - news) -week gas prices rise on expected Troll field outage

* Friday gas price dips on oversupply

July 3 (Reuters) - British wholesale gas prices for day-ahead and next-week delivery rose on Friday as traders expected pending maintenance at Norway's giant Troll gasfield to restrict supply.

Gas prices for immediate delivery, however, was down 0.30 pence per therm to 43.10 p/therm as of 0924 GMT owing to an oversupplied national network.

Maintenance at Troll begins on Saturday and is expected to lead to reduced flows via Norway's Langeled pipeline, the UK's biggest single import source.

The outage is expected to reduce Norway's export capacity by 51 mcm/day, lowering Langeled deliveries to 20 mcm/day, analysts at Thomson Reuters Point Carbon said.

Langeled flows on Friday were seen at 44 mcm/day.

Gas for weekend delivery traded at 43.35 p/therm, up 0.25 p/therm while gas for Monday delivery was up 0.65 p/therm at 43.70 p/therm.

Britain's gas network was oversupplied by 9.1 million cubic metres (mcm) per day with demand pegged at 182.3 mcm/day, according to National Grid (LSE: NG.L - news) data.

Britain exported around 37 mcm/day to Belgium via a sub-sea link on Friday morning, but analysts expected the Troll outage to reduce Britain-to-Belgium exports to around 30 mcm/day.

Imports from the Netherlands were at zero.

An unplanned outage at Centrica (LSE: CNA.L - news) 's North Morecambe gasfield has stopped production due to a technical process issue, with flows expected to resume at midday, Centrica said.

Analysts were looking ahead to the outcome of Greece's referendum on its bailout terms on Sunday given its potential impact on the euro. A stronger British pound versus the euro is bearish for UK gas prices.

Another external factor of note was Ukraine's decision to halt Russian gas imports.

Analysts at Energy Aspects estimated that Ukraine will need to import around 700 mcm of gas per month from Europe between now and September in order to refill its storage sites for winter and to avert disruption to transit supplies bound for Europe.

Russian gas flows to the European Union via Ukraine were unaffected on Friday.

Gas prices for winter 2015 delivery were unchanged at 47.70 pence per therm.

Dutch day-ahead gas prices at the TTF hub were 0.05 percent lower at 21.02 euros per megawatt-hour.

Europe's benchmark carbon price was 0.13 percent lower at 7.45 euros per tonne on ICE Futures Europe. (Reporting by Oleg Vukmanovic; editing by Jason Neely)