Russian border guards began pulling the Arctic Sunrise ship to a nearby port on Friday, Greenpeace reported on Twitter.
"At this moment, the Arctic Sunrise ship is being taken to the port of Murmansk," the environmental group said.
The move comes a day after Greenpeace reported that the Russian Coast Guard had stormed the ship which had been protesting drilling by Russia's state-run oil giant Gazprom.
"The Coast Guard illegally boarded Greenpeace's ship, the Arctic Sunrise," late Thursday, the group posted online. "Activists are currently being held at gunpoint."
"According to the statement, around 15 armed men boarded the ship in the Barents Sea by lowering themselves on ropes from a helicopter at around 7 p.m. local time (1600 UTC). They then began aggressively moving the activists into a single compartment on board the ship.
"No one has been hurt, and spirits are high. The crew is however not in control of the ship at this point," Greenpeace wrote on Twitter.
Greenpeace insists its Dutch-flagged ship was in international waters at the time of the raid.
'Disaster waiting to happen'
Among the detained activists are two Greenpeace members captured by Russian coastguards on Wednesday. The two men from Finland and Switzerland were seized while attempting to scale the Gazprom-owned Prirazlomnaya oil platform.
On Thursday Moscow said it had summoned the Dutch ambassador to Russia, Ron van Dartel, to issue a protest over the activists' attempt to scale the platform.
The activists acted in a "provocative and life-threatening manner that might lead to an ecological catastrophe," the foreign ministry said in a note delivered to van Dartel on Wednesday.
Vladimir Chuprov of Greenpeace's Russian office rejected the allegations, saying the ship had not violated any laws.
The Greenpeace ship has been protesting a plan by Gazprom to start production from the Prirazlomnaya platform in 2014.
It argues that the world's largest gas company risks causing a catastrophic oil spill in an area with three nature reserves that are home to polar bears, walruses and rare seabirds, describing the oil platform as "an Arctic disaster waiting to happen".
ccp/dr (AFP, AP, Reuters)