LONDON, May 18 (Reuters) - Dutch wholesale gas prices rose for a second day on Wednesday amid ongoing uncertainty over supply disruption as a deadline for buyers to pay in roubles for Russian gas approaches.

The Dutch day-ahead contract was up 2.9 euros at 49.80 euros per megawatt hour (MWh) by 0913 GMT, while the benchmark front-month contract for June delivery was up 1.4 euros at 95.80 euros/MWh.

The European Commission said on Tuesday opening accounts in roubles at a Russian bank to pay for gas would breach the bloc's sanctions against Moscow, after Brussels released updated guidance on how companies can legally keep buying Russian fuel.

Russia has cut supplies to Poland and Bulgaria in a dispute over the rouble payment method, but several companies had indicated over the past few days they thought they would be able to make payments without breaching sanctions.

"We're getting closer to the payment date. So far consumption is low and tonnes of gas are flowing in. However, power is now an issue and... lower production in Norway, Finland, and France mean that things are still on the up," a European gas trader said.

He added that a request by Finland and Sweden to join NATO had added some potential for escalation on the political side too, keeping prices around the 100 euro level.

In the British market, prices were up, with the day-ahead contract rising 14.50 pence to 97.50 pounds a therm. The contract for immediate delivery was also up earlier in the session before easing to trade flat by 0916 GMT.

Prices were supported by a slowdown in LNG deliveries, with traders saying several cargoes have been diverted to Spain and several ships queuing to access the ports.

The UK system was 14.8 million cubic meters (mcm) oversupplied on Wednesday.

Refinitiv analysts said stronger Norwegian maintenance is also a factor, with UK exports likely to fall as it receives less gas from Norway.

In the European carbon market, the benchmark contract fell by 3.72 euros to 88.00 euros a tonne. (Reporting by Marwa Rashad; Editing by Jan Harvey)