Chinese authorities in the northwestern Muslim region of Xinjiang have arrested 139 people accused of spreading religious extremism online.

Those arrested had posted a variety of content about jihad on the internet, including videos depicting terrorist attacks or showing how to make homemade explosive devices, state-run Xinjiang Daily newspaper reported.

"Jihadists and terrorists are the enemy of all human races," said Luo Fuyong, a spokesman for the Xinjiang government.

Beijing has recently launched a crackdown on online dissent, tightening sanctions against those critical of the government's rule.

Xinjiang is home to the Uighur minority, a Turkic-speaking predominantly Muslim ethnic group, and witnesses periodic outbreaks of anti-government and anti-Chinese violence.

The Uighur, who are the largest ethnic group in Xinjiang, complain they are discriminated against by Chinese ethnic Han migrants who have flooded into the region in recent decades.

Uighur activist Dilshat Rexit, who is a spokesman for the Germany-based World Uyghur Congress, which Beijing designates as a separatist group, claimed Chinese authorities are using charges of spreading jihad as an excuse to crack down on Uighurs.

"[Those detained] had expressed discontent with Chinese rule and systematic repression in the area", Rexit told AFP.

According to official statistics, about 45% of Xinjiang's population is Uighur while 39% is Han. However Han dominate the economy.