* Russian Foreign Ministry summons Dutch ambassador to complain over the protest
* Russian coast guards still hold two activists after Wednesday stunt - Greenepeace
* Russia's first Arctic oil rig expected to start production in 2013 after delays
MOSCOW, Sept 19 Russia accused the environmentalist Greenpeace group on Thursday of 'aggressive and provocative' actions in boarding a Russian oil platform in the Arctic, an area ecologists say is imperilled by a rush for its resources.
Russian coast guards in the Barents Sea fired warning shots on Wednesday and arrested two Greenpeace activists from the Amsterdam-registered 'Arctic Sunrise' ship who scaled the side of the Gazprom-owned Prirazlomnaya platform.
Prirazlomnaya is Russia's first Arctic offshore oil rig and a sensitive project in a country that has made tapping the region's resources a priority to drive its economy. Greenpeace activists had boarded the platform previously in August.
The Russian Foreign Ministry said the action had threatened the site's security and it had summoned the Dutch ambassador on Wednesday, asking him to ensure it was not repeated.
"The intruders' actions were of aggressive and provocative character and had the outward signs of extremist activity that can lead to people's death and other grave consequences," the ministry said in a statement.
Two activists - one with Swiss citizenship, the other from Finland - were still being held by Russian coast guards after the protest, Greenpeace said, in a statement that dismissed Russia's criticism of the protest.
"Let's be absolutely clear about this: the real threat to the Arctic comes not from Greenpeace but from oil companies like Gazprom that are determined... to drill in remote, frozen seas," said Ben Ayliffe, the green group's Arctic oil campaign head.
The Arctic is estimated to hold 13 percent of the world's undiscovered oil reserves and 30 percent of its undiscovered natural gas.
But environmental campaigners say the rush for the Arctic's natural resources threatens to destroy its fragile ecosystems and says there is insufficient emergency planning in case of an oil spill in its extreme conditions.
Global majors including ExxonMobil, Eni and Statoil have agreed to enter Russia's Arctic waters and Norway is pushing ahead with its own drilling plans.
But technical difficulties, high costs and mishaps as well as determined campaigns against the Arctic drilling have now brought greater hesitation among some players.
Developing the Prirazlomnoye oil deposit, located in the Pechora Sea some 60 km (40 miles) from Russia's northern coast, was already delayed last year with Gazprom blaming technical problems. It is expected to reach peak production of 6 million tonnes per year (120,000 barrels per day) in 2019.