Yekaterina Zaspa, a Russian doctor with Greenpeace's Arctic Sunrise icebreaker, was released on bail of two million rubles (USD 61,400, 45,500 euros), the group said, citing the ruling of Saint Petersburg's Kalininsky court.
Earlier today, another Saint Petersburg court extended the pre-trial detention of Australian activist Colin Russell until February 24, meaning he could remain in jail until the 2014 Winter Olympic Games in Sochi end on February 23.
The 30 activists from 18 countries were put in pre-trial jail in September after Russian security forces seized their ship at gunpoint following an open-sea protest against Arctic oil drilling.
They were first charged with piracy, which carries a maximum sentence of 15 years, but the charges were later changed to hooliganism, which carries a sentence of up to seven years.