Rights groups have condemned China for charging a prominent Uighur critic of government policy towards his mostly Muslim minority with inciting separatism – a crime that can carry the death penalty.
The whereabouts of Ilham Tohti, an economics lecturer at a Beijing university, is unknown to his family and supporters. But his wife, Guzaili Nu'er, said she had been informed of the charges.
Tohti has been one of the most high-profile critics of Chinese policy in Xinjiang, the vast western region where most Uighurs live.
Dilshat Rexit, a spokesman for exiled group the World Uyghur Congress, said: "We call on the international community to monitor China and free this Uighur scholar."China's accusations of separatism are merely an excuse for suppression of those with different political opinions."
The US-based Uyghur Human Rights Project said the charge against Tohti "reflects not only a zero-tolerance policy to Uighur dissent, but also the growing intractability of China towards international criticism of its ethnic policies".
The group also called on China to account for the whereabouts of Tohti, who has not been allowed to contact his family or see a lawyer since his arrest last month.
China maintains that unrest in Xinjiang is caused by terrorist groups seeking an independent state. This account is denied by Uighur rights groups, which complain of widespread religious repression and economic discrimination.
Tensions in Xinjianghave risen in the past year with a series of deadly clashes between locals and China's security forces.
Police also accused suspects from the region of deliberately crashing a car in Beijing's Tiananmen Square in October, killing two tourists and the three people in the vehicle.
The incident led the Chinese president, Xi Jinping, to call for a security push in Xinjiang. Tohti had challenged the government's account of the crash.
The US and the European Union have both condemned Tohti's arrest.
China's courts are tightly controlled by the ruling Communist party, and have previously handed lengthy jail sentences to intellectuals who have spoken out against the authorities.
