Uighur journalist Hairat Niyaz, detained by Chinese authorities since 1 October, faces imminent torture and ill-treatment, Amnesty International warned.
The organization has called on Chinese authorities to release Hairat Niyaz immediately and unconditionally, or charge him with a recognizable criminal offence.
A detention notice delivered by the police to the family of Hairat Niyaz on 4 October, said that he is under investigation for "endangering state security".
Police told Hairat Niyaz's family that he was detained because he gave too may interviews to various media.
Family and Uighur community friends believe his detention is due to his comments about the real cause of the recent unrest in the Xinjiang Uighur Autonomous Region (XUAR).
Hairat Niyaz has argued that the core problems that led to the disturbances are 20 years of discriminatory ethnic policies including using "anti-terrorism" to target Uighurs, marginalization and economic issues.
He warned the local authorities of possible disturbances the day before the unrest erupted in July. His warning was ignored at that time, but was later used to place him under investigation.
As many as 156 people were killed when violence and widespread unrest broke out in Urumqi and in other parts of the XUAR on 5 July. The violence followed a police crackdown on initially peaceful demonstrations in Urumqi by Uighurs.
The demonstrators protested the authorities' initial inaction following the death of two Uighur workers during a violent riot at a factory in southern China (Shaoguan, Guangdong province).
In the aftermath of the violent crackdown, the authorities accused overseas Uighurs, in particular the World Uighur Congress and its President Rebiya Kadeer, of having masterminded the unrest.
Following the July unrest the authorities detained thousands of people.
They are reported to have brought dozens to trial and threatened those involved in the unrest with harsh sentences. This month, the authorities announced the first death sentences for 11 individuals involved in the protests.
The authorities have interpreted all dissent as stemming from "terrorist" or "separatist" activities, justifying their harsh crackdown while ignoring underlying sources of the discontent.
Hairat Niyaz was taken from his home in Urumqi by XUAR internal security police on Chinese National Day.
He has not been able to meet with a lawyer of his choosing or with his family since his detention. He is being held at Tianshan detention centre in Urumqi.
Amnesty International has urged the Chinese authorities to guarantee that Hairat Niyaz is not tortured or otherwise ill-treated while in custody.
The organization has also called on the authorities to ensure that he is given access to a lawyer of his choice, his family and any medical treatment that he may require.