Russia’s energy company Gazprom says its Arctic offshore Prirazlomnoye field has started to produce oil.

Chief Executive Officer Aleksei Miller said in a statement on December 20 that “we have become the pioneers of Russia’s Arctic development.”

The start of production at Prirazlomnoye had long been delayed due to challenges including aging equipment and a change in the project’s shareholders structure.

The project has been criticized by environmentalists who say it could threaten the delicate Arctic ecosystem through oil spills.

Russia detained 30 Greenpeace activists protesting against Arctic drilling at the Prirazlomnaye platform in September.

The protesters faced jail sentences of up to 7 years until Putin announced an amnesty, which covers the activists.