The human rights activist and Nobel Peace laureate Tawakkol Karman is mourning the death of China's most prominent jailed political activist, Nobel Peace Prize laureate Liu Xiaobo.

Chinese authorities confirmed Mr. Liu died from multiple organ failure after not being allowed to leave the country for treatment; his request to receive liver treatment abroad was repeatedly denied by his country’s authorities. 

Liu, aged 61, had been serving an 11-year jail sentence on charges of inciting subversion with his pro-democracy writings when he was diagnosed with late-stage liver cancer in May.

“Nobel Peace Prize laureate Liu Xiaobo, who was known for his defense of democracy and human rights, will be remembered by the world as a real hero,” wrote Karman in social media.

She added that Xiaobao's death will not end the cause for which he had been fighting, pointing out that this fact is a lesson that must be understood by those who have doubts about the triumph of freedom and democracy.

Liu’s death sparked an immediate wave of international mourning and condemnation.

The Norwegian Nobel Committee held China responsible for the ‘premature’ death of Xiaobo, saying: “The Chinese government bears a heavy responsibility for his premature death.” 

It also expressed deep concern about the situation of Liu Xia, the widow of Nobel laureate Liu Xiaobo, after his death on Thursday. 

The German chancellor, Angela Merkel, paid tribute to “a courageous fighter for civil rights and freedom of opinion.”

China’s 2010 the Nobel Peace Prize has become the first Nobel laureate to die in custody since German pacifist Carl von Ossietzky, the 1935 recipient, who died under surveillance after years confined to Nazi concentration camps.