More than 160 people have been hospitalised and hundreds of others have been sickened in northeastern China in a suspected case of pollution caused by a chemical plant, local media said Thursday.

Staff at a plant operated by the Jilin Chemical Fibre Group in Jilin city, as well as residents living nearby, started complaining of headache, nausea, vomiting and general fatigue in late April, the Beijing Times reported.

About 1,000 people reported suffering from the symptoms and 161 of them had to be hospitalised, the paper said.

Patients said they suspected they had been affected by emissions from Connell Chemical, a Hong Kong-invested chemical producer near the fibre plant, according to the report.

Environmental authorities have tested the air near the two chemical companies but have not yet been able to identify any pollutant, it said.

However, the city government has ordered Connell Chemical to shut down its aniline plant and inspectors are staying on the spot to track the air quality 24 hours a day, the report added.

China's health ministry has sent disease control experts to the city to assess and analyse the impact of the suspected pollution, it said.

Aniline is a colorless, oily and poisonous organic compound used to make rubber, dyes, pharmaceuticals and varnishes.

China, the world's largest producer and consumer of coal, is struggling to clean up its skies after decades of rapid economic development.

A survey conducted in November in 320 cities said the average air quality in two out of five Chinese cities ranged from "polluted" to "hazardous", state-run Xinhua news agency reported.