Seven students of a prominent scholar from China's Uighur minority have been convicted of separatism in a secret trial and given prison sentences of three to eight years, a lawyer said Tuesday.

They were students of Beijing economics professor Ilham Tohti, who was convicted of separatism in September and sentenced to life in prison.

The move was seen as part of Beijing's efforts to silence criticism of government policies in the violence-wracked far-western region of Xinjiang, home to the mostly-Muslim Uighur group.

A court in the regional capital Urumqi Monday found the seven guilty of actively aiding in Tohti's "separatist activities", his lawyer Li Fangping said.

"The sentences were not as severe as I had expected," he told AFP.

One student was given eight years behind bars, with the shortest sentence being three years, said Li, who did not represent the students but has been in contact with their lawyer, who has declined to be named.

China blames attacks and clashes in Xinjiang, which have claimed several hundred lives in the past year, on terrorists seeking independence for the region, while rights groups say official repression of Uighur religion and culture has stoked violence.

Six of the students are Uighurs while one is a member of China's Yi minority, the state-run Global Times newspaper reported.

The paper added they were alleged to have helped maintain Uighur Online, a bilingual website launched by Tohti.

Authorities have previously described Uighur Online as "a platform... to create conflicts, spread separatist thinking, incite ethnic hatred and advocate 'Xinjiang independence'", the Global Times reported.

AFP was not able to find any articles supporting independence for Xinjiang on an archived copy of the website, which authorities deleted after Tohti was detained.

Tohti, 45, has said the site was intended to encourage communication between Uighurs and China's Han majority. While he had been an outspoken critic of China's policies towards Uighurs, he repeatedly told reporters that he opposed independence for the region.