His arrest is seen as part of a broader crackdown on what the government says is violence carried out by Islamist militants and separatists there.

"He said he is still in leg irons. Urumqi is already cold, but he is still wearing short sleeves and he has fallen ill. He has not been given the clothes his family sent to him," Tohti's lawyer Li Fangping said after meeting him on Monday.

"Given the situation, his spirits are actually quite good."

Prosecutors have denied a request to have the trial moved from Urumqi to Beijing, where Tohti lived, worked and operated a Uygur-language website, Li said.

The treatment of Tohti in custody also violated the country's laws, he added.

Several of Tohti's students, who had worked on the website, have also been detained.

"They won't even give him access to photos sent by his family," Li said.

"After a month they say they are still evaluating the pictures. They are worried that there are secret codes in the pictures."

The court could not be reached for comment.

Activists say the government's repressive policies, including controls on Islam, have provoked unrest that has pitted Uygurs against the mainland's ethnic Han majority.

Beijing denies that. It says militant groups in neighbouring south and central Asian countries are promoting separatism and violence on the mainland, although it has offered little evidence and experts have questioned the extent of the links.

Tohti, who taught at Beijing's Minzu University, has said he never associated with any terrorist organisation or foreign-based group and has "relied only on pen and paper to diplomatically request" human rights and legal rights for Uygurs.