Police and a rights group in northwest China said Monday that hundreds of Muslims fought with police, when authorities declared a newly-built mosque illegal and moved in to destroy it.

The Hong Kong-based Information Center for Human Rights and Democracy said two people were killed and 50 injured when police used tear gas, knives and batons to beat back ethnic Hui Muslim protesters in Hexi township Friday.

Township police denied there were any deaths, but said several people had been detained. About 1,000 police destroyed the mosque after the clash.

China's communist government closely monitors religious activity and worries that mosques and churches might become centers for anti-government agitation.

The Hui people are members of one of several Muslim minority groups in China. They include descendants of Muslim immigrants from Central Asia, members of China's majority Han ethnicity who converted to Islam, and several other groups.