The Switzerland-registered operator of Nord Stream 2, Russia's controversial gas export project, has started pre-commissioning activities to start filling the first leg of the Baltic Sea line with gas.

The eponymous operator said Russian pipelay barge Fortuna performed an above-water tie-in on 10 June in German maritime sector, joining the final two offshore section of the previously laid pipeline.

Are you missing out on ACCELERATE?
Gain valuable insight into the global oil and gas industry's energy transition from ACCELERATE, the free weekly newsletter from Upstream and Recharge.

Earlier, Nord Stream 2 executives said that commissioning of the two legs of the pipeline - which stretches for about 1200-kilometres - is not expected to take much time, because the pipeline will not be filled with water for pressure testing.

Compared to Russia's first gas export pipeline to Germany - Nord Stream - the operator has employed more rigorous welding and production controls, bypassing the need for water pressure test, according to executives.

Nord Stream 2 said offshore pipelay work on the second leg is continuing in the Danish maritime sector.

The pipe is being laid by another Russian vessel, the Akademik Chersky, that has been moving slowly along the route of the second uncompleted leg, using an anchor positioning system to advance itself.

The offshore segments of the second leg are now expected become interconnected in October.

Poland and Ukraine raise critical objections

Meanwhile, a recent decision by the US President Joe Biden to halt efforts to block the Nord Stream 2 offshore construction work, has been criticised in Poland and Ukraine itself.

US officials indicated they favoured a switch to talks with Germany to provide Russian gas transit guarantees to Ukraine and other Eastern European states after Nord Stream 2 enters service.

Technically, Russian gas monopoly Gazprom has contracted to continue gas supplies to Europe via Ukraine and Slovakia until end of 2024.

However, Gazprom may start cutting transit gas flows across Poland soon after Nord Stream 2 becomes operational, because its long-term transit agreement expired last year, with the throughput capacity in Yamal-Europe transit line across Poland being awarded on spot tenders.

Polish foreign minister Zbigniew Rau raised concerns that his nation is being sidelined in talks between the US and Germany on the Russian gas pipeline.

"President Joe Biden equates Europe with Germany," Rau told the Polish largest daily newspaper Rzeczpospolita in an interview published on Friday.

"The US allies found no time to hold consultations with our region of the world, which is the most endangered by the results of the decision," Rau said.

The minister added that when he met US Secretary of State Antony Blinken in January, he was promised that "no decision [on Nord Stream 2] would be taken without us."

Elsewhere, the newly appointed head of the Ukraine’s gas importer and distributor Naftohaz Ukrainy, Yuri Vitrenko, flew to Washington this week.

According to Bloomberg, he was to deliver a message to US lawmakers that allowing the completion of the Nord Stream 2 pipeline would be a victory for Russian President Vladimir Putin and a blow to American credibility in Eastern Europe.