The Netherlands on Sunday said Greenpeace's right to peaceful protest was "indisputable" after the environmental group defied Russian authorities by deploying an icebreaker through an Arctic shipping route without permission.

Greenpeace on Saturday announced its ship, the Amsterdam-registered Arctic Sunrise entered the Northern Sea Route to protest against oil drilling -- despite being blocked by Russia on several occasions citing concerns about the icebreaker's ability to withstand thick ice.

"Greenpeace's right to a peaceful demonstration is indisputable," the Dutch Foreign Ministry said in a statement.

It added: "According to the data the Netherlands have on the ship, there is no reason to doubt its technical state."

But The Hague added that countries bordering the Northern Sea Route were "allowed to have additional legislation for ships, to ensure safe and responsible use of the route."

The Hague contacted Moscow on Friday "to see how Greenpeace in the short term could meet... requirements" but was yet to receive an answer.

"We are in constant contact with Greenpeace and the Russian authorities and we have urged restraint and good communication on both sides," the statement added.

The Arctic Sunrise was heading into the Kara Sea on Saturday where several vessels contracted by Rosneft, Russia's top oil firm and its US partner ExxonMobil, are conducting seismic testing to prepare for offshore drilling near the Russian Arctic National Park.

The Russian transportation ministry has accused the Dutch-flagged vessel of "crudely" violating Russian and international law, with the global environmental group in turn calling Russia's move a "thinly veiled attempt to stifle peaceful protest."

Greenpeace says the plans to drill in the protected ecosystem were in contravention of Russia's own laws.

Established in 2009, the natural park is home to endangered species such as the bowhead whale and is a major breeding ground for polar bears.

Rosneft, headed by one of President Vladimir Putin's closest confidants, Igor Sechin, said its offshore operations were "absolutely safe".

Russia and the United States hope that the global warming melting the Arctic sea ice will help them tap the vast oil and gas resources believed to be buried in the region.

Putin has pledged to turn the Northern Sea Route into a key shipping artery, part of the Kremlin's bid to mark out its stake over the energy-rich Arctic.