The Netherlands said Monday it has taken Russia to the world's maritime court in order to free 30 crew members of Greenpeace's Arctic Sunrise, charged with piracy after protesting Arctic oil drilling.

"The (Dutch) state is asking for the freeing of the detained crew and the release of the Greenpeace ship," before the German-based International Tribunal for the Law of the Sea (ITLOS), a statement said.

"Because the Netherlands find that the ship's release and the freeing of the crew is an urgent matter, it has now decided on this step," it added.

Russian authorities have charged the environmental group's crew members with piracy, which carries a 15-year sentence, after they staged a protest against Arctic oil drilling last month.

The activists from 18 different countries have been placed in pre-trial detention until late November in the northern Russian city of Murmansk.

Last week, a Murmansk court rejected several bail requests, ignoring a worldwide campaign to have the piracy charges dropped.

Although the Netherlands is calling for the crew to be freed, it has in the past also said Russia had the right to try them.

The Dutch government said it expected a hearing within the next two to three weeks before the Hamburg-based tribunal.

"A decision is expected within a month from today," the Dutch statement said.

The UN-backed tribunal based in the German northern port city opened its doors in 1994, shortly after the UN's Convention of the Law of the Sea came into force.

It has the power to make rulings based on the Convention, which spells out the law and rules governing the world's oceans, seas and resources.

The legal action before the tribunal is the second step in the Dutch government's attempt to have the Greenpeace activists released.

Earlier this month The Hague started legal action against Russia in the form of an arbitration process, but warned if no progress was made it would take the case to the maritime tribunal.

The arbitration procedure "is being continued," the Dutch statement said on Monday, with Foreign Minister Frans Timmermans stressing in the past he preferred a diplomatic solution.

Russia now had to name an arbitrator before November 3, a step already taken by the Netherlands.

In total five arbitrators, including one from each country are needed to try and solve the case.

Should Russia not have named an arbitrator by November 3, the Netherlands "could ask the tribunal's president to name the outstanding four arbitrators," the statement said.

Based in Amsterdam, Greenpeace on Monday welcomed what it termed the "unusual step" by the Dutch government.

"Greenpeace applauds the Dutch government for taking these very important steps," said Greenpeace International's Jasper Teulings.

"However, it will likely take about four weeks before the Tribunal announces the verdict," he added, calling on all governments involved to work to speed up the process.

The September 18 protest saw several activists scale the oil platform in the Barents Sea to denounce Russia's plans to drill in the Arctic.

Russian border guards then lowered themselves onto the Dutch-flagged Arctic Sunrise from a helicopter, locked up the crew and towed the ship to Murmansk, located nearly 2,000 kilometres north of Moscow.

President Vladimir Putin has said that in his opinion the activists were not pirates but had breached international law by getting dangerously close to the oil rig.

The unusually tough charges have sparked comparisons with the case of the Pussy Riot punk rockers who were last year sentenced to two years in a penal colony for demonstrating against Putin in a Moscow church.

The Greenpeace arrests and an attack on a Dutch diplomat in Moscow, following the allegedly rough arrest of a Russian diplomat in The Hague, has caused a diplomatic flare-up between the two states whose friendship dates back to Tsar Peter the Great.

The spat is particularly embarrassing coming during a Russian-Dutch Bilateral Year aimed at promoting cultural ties.