NANNING - Four hydropower stations suspected of operating illegally in a nature reserve in South China's Guangxi Zhuang autonomous region have been closed, local authorities said Thursday.

The four hydropower stations, suspected to have been built illegally in the Qianjiadong National Nature Reserve in the tourist city of Guilin, have stopped operations, according to the regional water resources department.

An investigation jointly conducted by the regional environmental protection department and forestry department showed that the four hydropower stations failed to implement environmental impact assessment (EIA) procedures. The stations have also installed power lines and built plants, roads, dams and canals in the reserve since 1996.

The hydropower stations have violated the country's environmental protection law and forest law as well as nature reserve regulations, according to the investigation.

The stations stopped operations and those responsible for the construction have been detained and will be punished, the water resources department said.

The local government was urged to restore the environment in the reserve.