Reports from the Ningxia region of northern China say hundreds of Muslim villagers have fought with riot police who tore down a mosque.

Hong Kong-based human rights monitors said the trouble erupted on Friday after police declared the mosque an illegal structure.

The monitors say 50 people were injured and more than 100 detained.

Chinese officials confirmed a mosque was pulled down. They said there were injuries and some people were detained.

Reports of the incident have only just emerged. The details remain sketchy and accounts of the scale of the trouble vary.

The incident is said to have taken place in Taoshan village, near the town of Hexi in Tongxin county of the Ningxia Hui Autonomous Region, a sparsely-populated semi-desert area in northern China.

A party official in Ningxia told the BBC that the mosque in Hexi was an illegal structure, so they knocked it down.

According to the Hong Kong Information Center for Human Rights and Democracy (ICHRD) about 1,000 police officers clashed with villagers when they arrived to demolish a newly-renovated mosque.

But a policeman who only gave the name Ma, told AFP new agency: "Two police officers and two villagers got injured and several villagers were taken away by the police, but I don't know how many."

The Hui ethnic group - who mostly inhabit the region - are one of a number of Muslim minority groups in China.

In 2009, riots erupted in western Xinjiang province when nearly 200 people died after tensions flared between Muslim Uighurs and Han Chinese.