The defiant academic said the judgment was "unjust" and "trampled on the law", according to his lawyer Liu Xiaoyuan, citing Mr Tohti's brother who was present at the short hearing held at a detention centre in Urumqi, the capital of the restive far-western region of Xinjiang.

It came as veteran journalist Gao Yu, 70, appeared in court in Beijing to face charges of "leaking state secrets", and as lawyers for prominent human rights defender Pu Zhiqiang warned he faced upgraded charges.

Rights groups say the trio are among hundreds of human rights activists and intellectuals targeted in what has been a sustained crackdown on civil society since President Xi Jinping came to power, even as the leader espoused a desire to push for a stronger role for rule of law in China at a major party plenary session in October.

Mr Tohti, widely seen as a passionate but moderate voice in pushing for the rights of his fellow Uighurs, was jailed for life in September in a sentence labelled by rights groups as unprecedentedly severe for a prominent rights activist in China.

A similarly severe sentence looms for Mr Pu, a 49-year-old lawyer who has earned a fearsome reputation for defending China's best-known activists and dissidents. He was originally detained in May on public order charges, but prosecutors are now pursuing the significantly more serious allegations of "inciting to subvert state power" and "inciting ethnic hatred".

A heavy police presence outside the court in Beijing prevented journalists from accessing the trial of Ms Gao, who stands accused of "illegally obtaining" and reporting on an internal Communist Party document which purportedly warned cadres against "seven perils", including a stronger civil society and a free press.

The state-run China Central Television aired footage of the journalist confessing to police and expressing "deep remorse", but Ms Gao later told her lawyers she was forced into the confession because police made threats against her son.

The intensity of the crackdown on dissent is widely seen to reflect the party leadership's belief that any sign of weakening political control could jeopardise one-party rule.

"The party may think it is restoring public legitimacy by reining in the nascent and critical civil society," said Sophie Richardson, the China director of Human Rights Watch. "But in doing so, it sets back progress, risks increasing social pressure, and forecloses the possibilities of peaceful criticism that can help resolve grievances."