Russian authorities say they plan to prosecute almost 30 Greenpeace activists for protesting Arctic oil activities by gas giant Gazprom.
Investigative Committee spokesman Vladimir Markin said on September 24 that all the activists -- regardless of their citizenship -- will be charged with organized piracy.
If found guilty, they could face up to 15 years in jail and a fine of 500,000 rubles (about $15,500).
Russian Coast Guard personnel seized the Netherlands-registered icebreaker "Arctic Sunrise" with the activists onboard last week after they tried scaling the Gazprom-owned Prirazlomnaya platform, Russia's first offshore Arctic oil platform.
The Greenpeace protest was aimed at calling attention to the environmental risks of drilling for oil in Arctic waters.
The activists remain aboard the vessel, which arrived at a port near Murmansk on September 24.
Markin said the Greenpeace "attack" violated Russia's sovereignty.
"When a foreign vessel full of electronic technical equipment of unknown purpose, and a group of people calling themselves members of an environmental rights organization, try nothing less than to take a drilling platform by storm, inevitably doubts arise about their intentions," the spokesman said.
He added that the activists posed a danger to the work of the oil platform. "Such activities not only infringe on the sovereignty of a state but might pose a threat to the environmental security of the whole region," Markin said.
Maria Favorskaya, a spokeswoman for Greenpeace Russia, told RFE/RL on September 24 that none of the activists had been officially charged yet.
"First of all, I want to say that there have not been any formal charges yet. Our lawyers at Greenpeace International have not received any such documents," she said.
"Nothing is known yet, and no one is accused. That is -- a case must be opened against specific individuals on specific charges. Nothing like that has happened yet. We haven't seen this."
Greenpeace also said the activists, who are nationals of 18 countries, had been denied access to lawyers and consular officials for four days.
A spokesman for Russia's border officials said diplomats from the activists' home countries would be allowed onboard to meet with them later on September 24.
In Stockholm on September 21, Russian presidential chief of staff Sergei Ivanov described the Greenpeace protest action as "piracy, Somali-style."
Greenpeace International has rejected the accusations, calling them a desperate attempt by Russian authorities to justify the illegal boarding of its ship in international waters.
With reporting by Interfax, AFP, Reuters, RIA Novosti, and ITAR-TASS