(CNN) -- The captain of a Greenpeace icebreaker carrying 30 activists protesting Arctic drilling has declined a demand made at gunpoint by Russian authorities to sail it toward the Russian port city of Murmansk, a Greenpeace spokeswoman said Friday.
"Captain Pete has refused to sail the ship, so they're towing it," Molly Dorozenski told CNN in a reference to Pete Willcox, captain of the Arctic Sunrise. Late Thursday, about 15 members of the Russian coast guard seized the ship and those aboard by sliding down a rope hanging from a hovering helicopter.
The guards, armed with handguns and rifles, took the activists to the ship's canteen and broke down the door to the communications room, smashing the equipment, said Ben Stewart, head of media for the group. The captives were told they were going to be taken to Murmansk, in northwest Russia, he said.
The group documented the incident in tweets:
"Russian authorities onboard with guns," said one. "They are breaking into the comms room now."
Another one said this: "Latest from the deck: Crew are sitting on their knees on the helipad with guns pointed at them."
And yet another: "This is pretty terrifying. Loud banging. Screaming in Russian. They're still trying to kick in the door."
More than 12 hours later, Greenpeace International reported that its communication with those aboard the ship had been cut off.
But it also reported that some activists were able to conduct interviews by satellite phone from the ship's mess, where they were being held.
"Greenpeace International has not received any formal confirmation of possible charges, and the activists have been denied access to legal or consular assistance," it said in a statement. "Over 20 Greenpeace offices are organizing protests at Russian embassies around the world today."
"They have done nothing to warrant this level of aggression and have been entirely peaceful throughout," said Ben Ayliffe, the head of Greenpeace International's Arctic oil campaign.
"The real threat to the Russian Arctic comes not from the crew of the Arctic Sunrise but from Gazprom, one of the most reckless oil companies in the world today," he said.
Willcox, who grew up in South Norwalk, Connecticut, is the son of a yachtsman and has been a skipper for Greenpeace since 1981, according to a posting on the Greenpeace website.
He was at the helm of the group's Rainbow Warrior in 1985, when it was bombed, Dorozenski said. "So, he's been around the block a few times."
A media officer with the border patrol in Murmansk said that none of the activists was under arrest and that the ship was being escorted to Murmansk, where crew members will be questioned about the possibility that they broke the law related to exclusive economic zones.
The Dutch have demanded that those aboard, including two Dutch nationals, be released immediately, said Friso Wijnen, a spokesman for consular affairs with the Dutch Ministry of Foreign Affairs. Dutch officials were in contact with Russian Embassy staff in Holland, and their own embassy staffers in Moscow were in contact with Russian officials, he said.
The other detainees are from Argentina, Australia, Brazil, Canada, Denmark, the United States, Britain, New Zealand, Ukraine, Russia, France, Italy, Turkey, Finland, Switzerland, Poland and Sweden, the group said.
The ship was sailing under the Dutch flag, RIA Novosti said.
The state-run Russian news agency said that Moscow had announced it gave a note to the Dutch ambassador expressing concern about a protest Wednesday in which the activists scaled an oil rig operated by a Gazprom subsidiary to call attention to its drilling plans.
"Gazprom is using out of date kit to drill in one of the most extreme environments on the planet," the group said in a tweet on September 17. "We can't let that happen."
Russian border guards fired warning shots at the environmentalists' ship and detained two activists -- Finnish and Swiss nationals -- but returned them during Thursday's standoff, RIA Novosti said.
No official comment from the guards was available, it added.
"The violators' actions were of an aggressive and provocative nature and had the appearance of extremist activity capable of causing human deaths and other grave consequences," Russia's Foreign Ministry said in a statement on its website, according to RIA Novosti.
CNN's Ross Levitt, Saskya Vandoorne and Alla Eshchenko contributed to this report.