A Russian court ordered 20 Greenpeace activists to be held in custody for two months over an Arctic oil drilling protest, pending an investigation.

They were detained when their vessel in the Barents Sea was seized by the Russian coast guard after two of the activists tried to scale an offshore oil rig belonging to state-controlled Gazprom.

Russian authorities have called the protest an attack. They've opened a criminal case on suspicion of piracy although the activists have not yet been charged.

Russian President Vladimir Putin:

(SOUNDBITE) (Russian) RUSSIAN PRESIDENT VLADIMIR PUTIN, SAYING:

"I don't know details of what has happened there, but it is absolutely evident that they are, of course, not pirates, but formally they were trying to seize that platform."

The detained included deck hands, cooks, and the ship's American captain, said Netherland's-based Greenpeace International.

One Chinese climate change campaigner weighed in on the detentions:

SOUNDBITE) (English) GREENPEACE CLIMATE CHANGE CAMPAIGNER, PRENTICE KOO, SAYING:

"We are doing the right thing because it is a peaceful petition and action against oil drilling in the Arctic and we are doing it for the sake of the environment. But the Russian government is doing it on no legal base."

Greenpeace called the detentions Soviet-style scare tactics by Russia.

Activists in Brazil, Mexico, China, Russia and Australia have protested their colleagues' detainment.