A chemical plant in central China's Hunan Province has been closed down over suspicion that it caused the lead poisoning of hundreds of local children.

Blood tests on more than 300 children in Dapu Township of Hengdong County found excessive levels of lead, indicating heavy metal poisoning, said the press office of the county government on Sunday.

The lead densities in their blood all exceeded the national standard of 100 micrograms per liter for children, with the tests revealing densities as high as 322 micrograms per liter.

Local authorities on Saturday set up an investigation team and shut down the Meilun Chemical Materials Limited Company.

Locals had reported it discharging untreated dust and waste water, both of which could have caused the children's poisoning.

Excessive amounts of lead in the blood harm the nervous and reproductive systems and can cause high blood pressure and anemia. In severe cases, it can lead to convulsions, comas and death.