A Greenpeace ship involved in a high-profile protest against drilling for oil in the Arctic has left Russia after being detained for 10 months, the environmental group has confirmed.

The Arctic Sunrise had been held in Murmansk since September after Russian security forces detained 30 people on board during a protest at state oil company Gazprom’s drilling platform.

In June Russia’s Investigative Committee told Greenpeace International that the arrest of the ship was annulled and a crew from the environmental group gained access to the vessel, spending three weeks making it seaworthy.

It has now set sail for its home port of Amsterdam, where its condition and any need for repairs will be assessed.

Greenpeace International Arctic campaigner Faiza Oulahsen said: “When the captain and crew boarded the Arctic Sunrise they found it in a bad state, with no maintenance for 10 months, and the ship’s navigation, communications and safety systems either removed or destroyed.

“The Arctic Sunrise is now headed for Amsterdam, where the ship will need to undergo extensive repairs so that it can get back to protecting the Arctic from reckless oil companies like Shell and Gazprom.”

She added: “The illegal boarding and arrest of the Arctic Sunrise and the ongoing investigation into the ‘Arctic 30’ protest was an attempt to intimidate and stifle debate about Arctic oil drilling — but it has only made us stronger.”

All 28 activists and two freelance journalists on board the Arctic Sunrise, including six Britons, were held in Murmansk and then St Petersburg, charged first with piracy and then hooliganism.

They were freed in December, granted amnesty under a new Russian law.