Prices highest since March on supply concerns

LONDON, Aug 25 (Reuters) - Dutch and British wholesale gas prices rose to their highest since March on Thursday in anticipation of Norwegian outages in September, lower French nuclear output and uncertainty about Russian gas flows after scheduled maintenance next week.

The Dutch contract for September delivery, a European benchmark, rose by 15.95 euros to 315.95 euros per megawatt hour (MWh) by 0918 GMT, the highest since March 7, while the December price was 30.55 euros higher at 319.75 euros/MWh.

The winter contract was 42.00 euros higher at 315.00 euros/MWh.

In Britain, the contract for immediate delivery rose by 82.00 pence to 580.00 pence per therm, and the contract for next day delivery surged by 72.15 pence to 579.65 p/therm, also the highest since March.

"September will bring heavy maintenance at the Norwegian Continental Shelf and at the same time we expect several coinciding outages at the exit terminals for Norwegian gas," said Kasia Piaskowska, gas analyst at Refinitiv.

Flows will be affected by maintenance and outages at several fields including Oseberg, Sleipner, Gullfaks and Gina Krog, as well as other facilities.

Added to this, Gazprom will halt natural gas supplies to Europe via the Nord Stream 1 pipeline for three days from Aug. 31 to Sep. 2, piling pressure on the region as it seeks to refuel ahead of winter.

The market is concerned that flows will not resume, even at the lower rate of 20% capacity currently, after the outage, traders said.

Russian pipeline gas supplies to Europe have dropped off by around 75% this year, impacted by a tug of war over European sanctions on Moscow over its invasion of Ukraine. https://tmsnrt.rs/3dMnW9G

"As long as European gas stocks are not full, injection demand should continue to support prices, along with gas demand for power generation which remains resilient," said analysts at Engie EnergyScan.

"In the meantime, only a decisive fundamental event or announcement could break the bullish momentum," they added.

Europe's gas storage sites were 78% full, Gas Infrastructure Europe data showed, getting close to a European Commission target of 80% by Oct. 1.

Several of EDF's nuclear power reactors in France have had their restart pushed back to at least mid-November in an adjustment of outage schedules, further delaying 5.2 gigawatts (GW) of supply at a time of historically low availability.

European power prices have surged to records because of the nuclear shortage as well as several other factors over the past several months.

In the European carbon market, the benchmark contract inched up by 0.09 euro to 89.33 euros a tonne.