British Greenpeace activist Anthony Perret, who was held in Russia following a protest over the country's Arctic drilling, said he was "chuffed" to be released.
Greenpeace's Arctic Sunrise Twitter feed states:
Anthony Perret, got out an hour ago, tells us "Chuffed to be out, it's quite nice really". #FreeTheArctic30
Great news: Kieron Bryan, the second Brit, has been released on bail in St Petersburg #FreeTheArctic30
More top news
Parts of the UK will feel colder than the Arctic Circle in the coming week as bitter winds make it feel -15C in some places.
At least three people have been killed in clashes in eastern Ghouta just hours after the UN Security Council backed a 30-day ceasefire.
Very Very Cold !