MOSCOW (AFP) – The environmental group Greenpeace said Thursday that it had lost contact with its ship protesting oil exploration in the Arctic after armed Russian officers stormed it and held the crew at gunpoint.
Greenpeace said it believes its Dutch-flagged ship Arctic Sunrise was in international waters when the raid began.
A day earlier its activists attempted to scale an oil platform owned by Russia's Gazprom energy giant in the Barents sea and Russian border guards arrested two activists.
"People armed with machine guns have descended on to the Greenpeace icebreaker Arctic Sunrise from a helicopter via ropes," Greenpeace said in a statement.
Activists said on the Twitter page of the Dutch-flagged Arctic Sunrise that the men, apparently Russian coastguards were "on board with guns."
"They are breaking into the comms (communications) rooms now," they said.
The group said it had then lost all contact with the ship, calling the boarding "illegal."
Russia said earlier Thursday it had protested to the Dutch ambassador in Moscow over "aggressive and provocative" actions by Greenpeace activists who scaled the oil platform Wednesday.
The foreign ministry said in a statement that it had summoned the Dutch ambassador to Moscow Ron van Dartel to protest "provocative actions" by the Arctic Sunrise and its activists.
It said the campaigners attempted to "infiltrate" the Prirazlomnaya platform, describing their actions as "aggressive and provocative" and "bearing the characteristics of extremist activity."
Their action "threatened people's lives and could lead to environmental catastrophe in the Arctic", the ministry said.
On Wednesday, the coastguard arrested two Greenpeace activists who tried to attach themselves to the platform in protest at Gazprom's activities in the Barents Sea, and was still holding them Thursday.
In a Greenpeace video released Wednesday, coastguard vessels are seen clashing with the activist boats, while an official on the Russian ship accuses the campaigners of "terrorism."
Greenpeace said that men on the coastguard boats wore balaclavas, fired over 20 shots, and slashed the activists' inflatable boats with knives.
The two arrested activists -- from Finland and Switzerland -- are still being held on the coastguard boat, said Vladimir Chuprov of Greenpeace's Russian office, describing their detention as groundless.
"The federal security service told our lawyer by phone that the activists were 'guests', while the border guard service said that they had been 'rescued'," Chuprov told AFP.
He also dismissed the foreign ministry accusations, saying the Dutch ship had not violated any laws.
Greenpeace said Gazprom -- the world's largest gas company -- intends to start production from the Prirazlomnaya platform in 2014, raising the risk of an oil spill in an area with three nature reserves that are home to polar bears, walruses and rare seabirds.
The organisation argues that the old oil platform is "an Arctic disaster waiting to happen."
Its director Kumi Naidoo asked President Vladimir Putin in a statement to "restrain the coast guard" saying the campaign group "has done nothing to warrant this level of aggression."
Greenpeace staged a similar action led by Naidoo against the same oil rig in August last year.
Gazprom has expanded its oil production operations in recent years and describes the oil field that the Prirazlomnaya will tap as an essential element of its oil business development strategy.