Greenpeace activists boarded two oil rigs in northern Europe Tuesday to protest against "reckless" plans by multinational companies to drill for oil and gas in the Arctic.

In the Dutch port of IJmuiden, members of the environmental group scaled the giant GSP Saturn platform which they say was on its way to the lucrative Dolginskoye oil field in Russia's northern Pechora Sea.

They chained the rig to a dock before six of them were briefly detained.

"The activists were later released with a warning to appear before a judge soon," Dutch police spokesman Koos Venema told AFP.

In Norway, 15 Greenpeace activists boarded the Transocean Spitsbergen oil rig, which is due to drill the Scandinavian country's northernmost well in the Barents Sea, a spokesman said.

The activists were still on board the Spitsbergen, with Greenpeace's Juha Aromaa telling AFP they had food and supplies "to stay on board for several days."

Venema said the activists in IJmuiden were detained after refusing a police order to abandon the GSP Saturn platform which the activists say is on its way to the lucrative Dolginskoye oil field in Russia's northern Pechora Sea.

Overnight in IJmuiden, Greenpeace divers and activists with climbing gear had surrounded the Saturn platform, which has been contracted by Russian state oil giant Gazprom.

"The divers chained the rig to the quay to prevent it from leaving the harbour," Greenpeace said in a statement.

'Hunt for last drops'

The Saturn rig, which has a crew of 100 and is the size of half a football field, is the second by Gazprom to be targeted by Greenpeace's campaign to highlight the dangers of oil drilling in the eco-sensitive North Pole area.

"The Arctic matters to us all, and protecting it demands a truly global response. We cannot let a reckless club of international oil companies hunt for the last drops as the ice melts away," Greenpeace International Arctic campaigner Ben Ayliffe said in a statement.

Russian security forces in September detained 30 Greenpeace activists and journalists and seized their Arctic Sunrise ship over the protest at an another offshore oil rig owned by Gazprom.

The 30, including four Russians, were detained for around two months before being bailed and then benefitting from a Kremlin-backed amnesty.

Greenpeace is now suing Russia before the European Court of Human Rights for detaining their activists.

"We will continue to campaign against Shell and Gazprom which want to use climate change to drill for oil in the vulnerable North Pole area," said Faiza Olahsen, who is one of the so-called "Arctic 30" activists arrested in Russia.

Both Gazprom and the largely Norwegian state-owned Statoil reacted with anger on Tuesday.

"Today, some thugs mounted the platform and deployed placards, but the platform has left the port and is following its planned route," Gazprom spokesman Sergei Kupriyanov told Moscow's Radio Echo.

Statoil accused Greenpeace of behaving "irresponsibly and illegally."

"Statoil respects the right for legal protests and believes it is important with a democratic debate on the oil and industry," the company said in a statement.

But "the safety of people and the environment is the first priority, and we do not want activity that can increase the risk level."

"When they still use this form of protest we believe they act irresponsibly and illegally," Statoil said.

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