UK GAS-Prompt prices rise as British supplies fall

* Supplies from UK continental shelf fall

* Ukraine and Russia fail to agree on gas imports

July 1 (Reuters) - British prompt gas prices rose on Wednesday on lower supplies from the UK continental shelf while injections into storage and exports to Belgium remained strong.

Gas for next-day delivery was trading 0.5 pence higher at 42.65 pence per therm at around 0830 GMT, while gas for immediate delivery was up 0.5 pence at 42.50 pence/therm.

National Grid (LSE: NG.L - news) data showed the system was largely balanced, with demand forecast at 191 million cubic metres per day (mcm/day) and supply at 189 mcm/day.

Traders said that lower than nominated deliveries from the UK continental shelf have added a risk premium to contracts, potentially leading to a tighter system.

Analysts at Thomson Reuters Point Carbon said flows from the UK continental shelf were almost 20 mcm lower than nominations from shippers would suggest.

With no reports of outages that could explain a drop, the reasons could be commercial as more gas became available from Norway after the Ormen Lange field returned to full production capacity.

In the Netherlands the day-ahead price at the TTF hub was broadly unchanged at 20.80 euros per megawatt-hour.

Further out on the curve, the winter 2015/16 contract rose by 0.28 pence to 47.80 pence per therm.

Ukraine halted natural gas imports from Russia on Wednesday after energy officials from the two countries failed to agree on quarterly prices, increasing the risk that it will not be able to refill its gas storage facilities before winter.

Russia's Gazprom said it halted supplies to Ukraine on Wednesday.

"If Russia and Ukraine are unable to agree on a gas price for third-quarter volumes, there may be an increased threat of disruption to gas flows to Ukraine," Point Carbon analyst Oliver Sanderson said.

Though Sanderson does not expect this to materialise, he said the risk could add upward pressure on prices despite bearish fundamentals.

Europe's benchmark front-year carbon price rose 13 euro cents to 7.50 euros a tonne.

(Reporting by Nerijus Adomaits; Editing by David Goodman)