Soviet-era dissident Lyudmila Alexeyeva, who became a symbol of resistance in modern-day Russia, has died at the age of 91.
The prominent activist passed away on Saturday afternoon in a Moscow hospital after a long battle with illness.
Ms Alexeyeva tirelessly defended human rights in the USSR from the 1950s, and continued to do so in Vladimir Putin's Russia.
'This is a huge loss for the entire human rights movement in Russia,' Mikhail Fedotov, head of the Kremlin Human Rights Council, said in a statement.
'It was not the first time that she was in this hospital, doctors had already revived her several times in the most difficult of situations. But there are situations in which doctors can do nothing,' he added.
'She had been struggling with illness recently, but her mind was always stronger than her body and far stronger than any disease.'
Kremlin spokesman Dmitry Peskov said Putin, of whom Alexeyeva was a strong critic, had sent a message of condolences to her family.
The president 'greatly appreciates Lyudmila Alexeyeva's contribution to the development of civil society in Russia and had great respect for her point of view on several issues concerning the life of the country,' Russian news agencies quoted Peskov as saying.
Alexeyeva had been the leader of the Moscow Helsinki Group, one of Russia's oldest human rights organisations which she helped found in 1976.
The group lamented the loss of a 'legendary, wise and humane person who remained a defender of human rights until the last moments of her life'.
Russia's rights ombudswoman Tatiana Moskalkova also mourned Alexeyeva.
'For those who have appreciated democracy in the past, for those who appreciate it now, and those who will appreciate it in the future, Lyudmila Mikhaylovna has always been and will always be a symbol of honesty and the uncompromising struggle for human rights,' Moskalkova told the Interfax news agency.
Alexeyeva, who trained as an archeologist, said that like many Soviet citizens she cried when the Josef Stalin died in 1953.
Her economist father and mathematician mother were both Communists who venerated Lenin.
But she lost confidence in the Soviet system when Stalin's crimes were revealed by new leader Nikita Khrushchev.
In the late 1950s, her apartment became a meeting place for the Soviet dissident intelligentsia, and a point for storing and distributing banned publications.
She campaigned against trials for dissidents, losing her job as a science publisher and enduring numerous searches and interrogations at the hands of the KGB.
With her security under threat, she left the USSR in 1977 to live in the United States, continuing her fight from afar through her writing.
She returned to Russia in 1993 with liberals hopeful of a new era after the Soviet Union's collapse under President Boris Yeltsin.
But Yeltsin's presidency collapsed into economic chaos and the horror of the first Chechen war, followed by a new clampdown on civil society after Putin took over in 2000.
After protests in the winter of 2011-2012 spawned hopes of a new beginning, the Kremlin responded with restrictions on non-governmental organisations.
Alexeyeva refused to register the Moscow Helsinki Group as a 'foreign agent' as required by a new law, instead cutting staff and foreign funding to get around the measure.
She slammed Moscow's seizure of the Crimea peninsula from Ukraine in 2014 for 'bringing shame on my country'.
The following year, she denounced the 'awful political killing' of opposition leader Boris Nemtsov.
She also tried to shed light on the fate of accountant Sergei Magnitsky, who died in prison after accusing Russian officials of tax fraud, and denounced the imprisonment of anti-Kremlin tycoon Mikhail Khodorkovsky.
On Alexeyeva's 90th birthday, Putin gave her a state award for 'outstanding achievements in the protection of human rights, and praised her 'courage'.
The European Parliament in 2009 awarded Alexeyeva the prestigious Sakharov Prize for defenders of human thought, along with the Memorial human rights group.
'If I save even one person, it's already a true joy,' she said at the time.
© Associated Newspapers Ltd.