China must punish the "brains" behind terrorists and fight against those who preach with "malicious intent", a state-run newspaper said Saturday in an editorial justifying the arrest of a prominent Uighur academic.

Ilham Tohti is an outspoken critic of government policy towards the mostly Muslim Uighur minority, who are concentrated in the far western region of Xinjiang which is regularly hit by unrest.

He was arrested Wednesday in Beijing and taken to an unknown place, his wife told AFP.

"Being a Uighur has made Tohti special, and he and the West seem to be taking advantage of this," the Global Times newspaper said, accusing the economist who teaches at the Central University for Nationalities of giving "aggressive" lectures.

"Freedom of speech and thought is encouraged on campus. But freedom has boundaries. Teachers with malicious intent should not be allowed to freely preach to students," said the editorial.

"The authorities must resolutely crack down on the terrorists, as well as the 'brains' behind them," it said, noting the "particularly close link between Tohti and the West" illustrated by the US State Department's "concern" over the fate of the academic.

Tohti, 44, was suspected of "committing crimes and violating the law", a Chinese foreign ministry spokesman said Thursday.

Supported by many academics and activists, he founded Uighurbiz.net, an information site on Xinjiang in Chinese and Uighur.

Tohti had been under constant surveillance, particularly when he travelled to Xinjiang.

He has been detained on a number of occasions in the past few years, including for more than a week in 2009 after his website ran reports on riots in Xinjiang which killed around 200 people.

The vast western area has for years seen sporadic unrest by Uighurs, which rights groups say is driven by cultural oppression, intrusive security measures and immigration by Han Chinese.

Beijing attributes the unrest to religious extremists and separatism.

In late October, police said three Uighurs drove a vehicle into crowds of tourists opposite Beijing's Tiananmen Square, killing two people and injuring 40, before crashing outside the Forbidden City and setting their vehicle ablaze. All three attackers died.

Tohti had warned against the temptation to stigmatise Uighurs after these events.

But according to the Global Times, "Tohti was attempting to find a moral excuse for terrorists".