BEIJING (Reuters) - Police in China's Xinjiang region are cracking down on people who promote jihad online, state media reported on Tuesday, amid a nationwide campaign against internet rumors that activists say is a blow to freedom of speech.

Sprawling Xinjiang is home to the mostly Muslim Uighur ethnic minority, many of whom harbor resentment of what they see as Chinese repression of their culture and religion. Some are campaigning for a separate Muslim state and there have been incidents of violence.

Xinjiang police were investigating 256 people for spreading "destabilizing rumors" online, the Xinjiang Daily newspaper said. Of those, 139 spread rumors about jihad, or Muslim holy war, or other religious ideas. More than 100 had been detained.

"Our local public security bureaus are strongly cracking down on those who engage in illegal activities online," the newspaper said. "Xinijang must not allow the internet to become a platform for crime."

Authorities frequently detain and arrest Uighurs for activities that they say extol religious militancy and ethnic separatism. But the latest crackdown is linked to a nationwide campaign against online rumors.

The newspaper did not say whether those detained were Uighur or from the majority Han ethnic group.

Rights activists say the action against internet rumors is a new way for authorities to curb criticism.

Dilxat Raxit, a spokesman for the exiled World Uyghur Congress, said the government campaign was aimed at stopping Uighurs from getting information on the Internet.

"Those Uighurs who were detained were expressing online their dissatisfaction at China's dominance of their localities and systematic repression," Raxit said.

Some of those detained had filmed videos or started groups on an instant messaging site that spread militant religious ideas, the newspaper said.

A farmer in the prefecture of Hotan was arrested after he uploaded material that authorities said contained separatist content, which violates Chinese law, the newspaper said.

(Reporting By Megha Rajagopalan and Ben Blanchard; Editing by Robert Birsel)

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