* Hamburg-based maritime court rules on law of the sea
* Russia declines to participate in court proceedings
* Tribunal ruling expected on Nov. 22
By Michael Hogan
HAMBURG, Nov 6 (Reuters) - The Netherlands asked an international court on Wednesday to order Russia to release 30 people detained during a Greenpeace protest against oil drilling in the Arctic at a tribunal Moscow refused to attend.
Dutch government representative Liesbeth Lijnzaad said Russia had "violated the human rights" of the activists who tried to climb onto Russia's first offshore Arctic oil rig in September, detaining them for seven weeks "without grounds".
Russia has said it does not recognise the case, accusing the activists and their ship, the Dutch-registered Arctic Sunrise, of posing a security threat. Prosecutors charged the 30 with piracy but then reduced the charge to hooliganism, which carries a maximum jail term of seven years.
President Vladimir Putin has said they are not pirates but has faced growing criticism in the West over what is seen as Russia's heavy-handed treatment of the case.
Countries have no right to seize vessels belonging to third countries in their exclusive maritime economic zones, Lijnzaad told the International Tribunal for the Law of the Sea in the German port of Hamburg.
Tribunal president judge Shunji Yanai set Nov. 22 as the provisional date for a court decision.
Another Dutch government representative, Rene Lefeber, told the court exclusive economic zones such as that where the Greenpeace ship was arrested gave nations rights to protect their natural resources but not the same powers to board and arrest vessels as they can in territorial waters.
As Russia's arrest of the vessel was illegal, other actions which followed this including the detention of the crew were also illegal, Lefeber said.
PIRACY AND HOOLIGANISM
The Hamburg court was established by the 1982 U.N. Convention on the Law of the Sea - of which both the Netherlands and Russia are signatories - to settle maritime disputes. Its decisions are binding but it has no means of enforcing them.
Greenpeace, a global environmentalist group based in Amsterdam, praised the Dutch bid to free the ship and crew.
"The Netherlands is taking a strong stance in support of the rule of law and the right to peacefully protest," Greenpeace international general counsel Jasper Teulings said after Wednesday's hearing.
Teulings said Greenpeace feared the 30 detainees still faced the piracy charges - which carry a maximum jail term of 15 years - despite a decision by the Russian committee handling the case to reduce them to hooliganism in late October.
"Nothing has changed despite the statement by Putin and from the investigative committee that the charges would be requalified to hooliganism," Teulings said.
Prime Minister Dmitry Medvedev last week reiterated Moscow's stance that Greenpeace posed a threat to the security of Russian workers and the environment by disturbing work at the platform.
The case has added to strains in relations between Russia and the Netherlands. On Tuesday, the Dutch foreign minister denounced a Russian law banning homosexual "propaganda" among minors and said violation of gay rights could be grounds for asylum in his country.