The 30 Greenpeace activists, including six Britons, were held last week when armed Russian officials boarded their vessel the Arctic Sunrise in the Arctic's Pechora Sea, near to oil company Gazprom's platform.
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The Greenpeace crew pictured aboard the Arctic Sunrise
The ship and protesters have been brought to the port of Murmansk, and Russian authorities said they were investigating charges of piracy, which carry a jail term of 10 to 15 years, against the activists.
Putin, speaking at a forum on Arctic affairs, said: "It's completely obvious they aren't pirates." But he added that Russian authorities did not know who was trying to seize the oil platform.
"Especially in view of the events in Kenya, really, anything can happen," he said, in a reference to the terrorist attack on a shopping mall in Nairobi.
Story continues after slideshow...
Greenpeace
(01 of11)
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The Greenpeace ship 'Arctic Sunrise', right, is escorted by a Russian coast guard boat in Kola Bay at the military base Severomorsk on the Kola peninsula in Russia, Tuesday, Sept. 24, 2013. Russian authorities have detained the Greenpeace ship 'Arctic Sunrise' and her 27 crew who face charges when they arrive at Murmansk following their attempt to protest arctic oil production. (AP Photo/Igor Podgorny, Greenpeace) (credit:AP)
(02 of11)
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In this image made available by Greenpeace, taken Tuesday, Sept. 24, 2013, crew members onboard the Greenpeace ship Arctic Sunrise display a "Save The Arctic" banner they created while under tow by the Russian Coast Guard. in Russia. The ship was boarded last week by Russian authorities after a peaceful protest against Arctic oil drilling. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Greenpeace) (credit:AP)
Greenpeace ship 'Arctic Sunrise'(03 of11)
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A crew member keeps watch aboard a Russian coast guard boat, left, as the Greenpeace ship 'Arctic Sunrise', right, is anchored next to it, in a small bay near Severomorsk, Russia, Tuesday, Sept. 24, 2013. The ship was boarded last week by Russian authorities after a peaceful protest against Arctic oil drilling. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Efrem Lukatsky) (credit:AP)
Greenpeace ship 'Arctic Sunrise'(04 of11)
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The Greenpeace ship 'Arctic Sunrise', center, is escorted by a Russian coast guard boat, left, in Kola Bay near the military base Severomorsk on the Kola peninsula in Russia, Tuesday, Sept. 24, 2013. The ship was boarded last week by Russian authorities after a peaceful protest against Arctic oil drilling. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Efrem Lukatsky) (credit:AP)
(05 of11)
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In this image made available by Greenpeace, taken early, Tuesday, Sept. 24, 2013, crew members onboard the Greenpeace ship, the Arctic Sunrise are briefed in the mess while under tow by the Russian Coast Guard, in Russia. The ship was boarded last week by Russian authorities after a peaceful protest against Arctic oil drilling. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Greenpeace) (credit:AP)
Greenpeace ship 'Arctic Sunrise'(06 of11)
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The Greenpeace ship 'Arctic Sunrise' is escorted by a Russian coast guard boat in Kola Bay at the military base Severomorsk on the Kola peninsula in Russia, Tuesday, Sept. 24, 2013. Russian authorities have detained the Greenpeace ship 'Arctic Sunrise' and her 27 crew who face charges when they arrive at Murmansk following their attempt to protest arctic oil production. (AP Photo/Efrem Lukatsky) (credit:AP)
(07 of11)
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In this image made available by Greenpeace taken early, Tuesday, Sept. 24, 2013, by a crew member onboard the Greenpeace Arctic Sunrise, the ship is being towed by the Russian Coast Guard vessel Ladoga towards Murmansk, in Russia. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Greenpeace) (credit:AP)
(08 of11)
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Greenpeace ship 'Arctic Sunrise' is escorted by a Russian coast guard boat, in Kola Bay at the military base Severomorsk on the Kola peninsula in Russia, at dawn Tuesday, Sept. 24, 2013. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Efrem Lukatsky) (credit:AP)
(09 of11)
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Greenpeace ship 'Arctic Sunrise' is escorted by a Russian coast guard boat, in Kola Bay at the military base Severomorsk on the Kola peninsula in Russia, at dawn Tuesday, Sept. 24, 2013. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Efrem Lukatsky) (credit:AP)
(10 of11)
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Greenpeace ship 'Arctic Sunrise' is escorted by a Russian coast guard boat, in Kola Bay at the military base Severomorsk on the Kola peninsula in Russia, at dawn Tuesday, Sept. 24, 2013. Russia has filed piracy charges against Greenpeace activists who tried to board an offshore drilling platform in the Arctic owned by state-controlled natural gas company Gazprom. (AP Photo/Efrem Lukatsky) (credit:AP)
Greenpeace ship 'Arctic Sunrise'(11 of11)
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The Greenpeace ship 'Arctic Sunrise' is escorted by a Russian coast guard boat in Kola Bay at the military base Severomorsk on the Kola peninsula in Russia, Tuesday, Sept. 24, 2013. Russian authorities have detained the Greenpeace ship 'Arctic Sunrise' and her 27 crew who face charges when they arrive at Murmansk following their attempt to protest arctic oil production. (AP Photo/Efrem Lukatsky) (credit:AP)
Greenpeace International executive director Kumi Naidoo said: "We welcome President Putin's recognition that our activists are clearly not pirates and acted purely out of concern for the Arctic environment.
"Our climbers attempted to attach themselves to the side of the platform to raise attention to the threat of Arctic oil drilling in this fragile environment and the urgent need to deal with climate change.
"This was a peaceful protest against Gazprom's ambitions to be the first company to pump oil from icy Arctic seas."
He added that claims that Russian border guards who confronted the activists were unaware who was behind the protest were "not credible".
"Our ship bears two large rainbows, two peace doves and has Greenpeace emblazoned on each side. They followed us for over 24 hours before the protest began. We have a long history of peaceful activism in Russia and are well known to the authorities."
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Putin was speaking at a forum on Arctic affairs
Greenpeace is campaigning against attempts by companies to extract oil from the waters of the Arctic, warning that a spill would be highly environmentally damaging and extraction of more fossil fuels will add to climate change.
Gazprom's plans to start drilling from the Prirazlomnaya platform in the first quarter of 2014 raised the risk of an oil spill in an area that contains three nature reserves protected by Russian law, campaigners said.