Ningxia Hui autonomous region has been found to have illegal construction projects in nature reserves and insufficient implementation of pollution controls, the Ministry of Environmental Protection said on Wednesday.

Ningxia is the fifth provincial region to be inspected by a team sent by the central government. A total of 57 polluting companies have been shut down, while another 179 companies have been required to improve their equipment to control pollution. Eight people have been detained and 105 officials have been held accountable, inspectors said.

In the autonomous region, 149 illegal construction projects have been found inside the nine national-level nature reserves since 2013.