MOSCOW  — The environmentalist group Greenpeace says two of its activists have been arrested after climbing onto an oil platform in Russia's Arctic waters. It claims warning shots were fired across the organization's ship.

A Greenpeace statement says the arrests were made Wednesday in the Pechora Sea, a section of the Barents Sea. The activists, who climbed a platform belonging to state gas company Gazprom, are being held on a Russian Coast Guard ship, according to Greenpeace.

The statement said the Coast Guard fired 11 shots across the Greenpeace ship that brought activists to the area.

A spokeswoman for the Federal Security Service, which includes the Coast Guard, said she had no immediate information on the incident.