The number of children showing lead poisoning which has been blamed on a nearby smelting plant in northern China has doubled to more than 600, state media reported.
Tests showed at least 615 children out of 731 living in two villages near the plant in Changqing township, Shaanxi province, had excessive lead levels in their blood, Xinhua news agency said late Thursday, citing the local Fengxiang county government.
A total of 166 would be hospitalised while the rest would be treated at home to rid their bodies of the excess lead, it said.
Authorities on Wednesday announced the closure of the Dongling Lead and Zinc Smelting Co. plant blamed for the poisoning but Xinhua said it had yet to be directly established if pollution by the company caused the children's illness.
Children living in other areas near the plant were also undergoing tests.
The lead levels in the blood of 300 children tested earlier ranged from 100 milligrams to 400 milligrams per litre, compared with normal levels of between zero and 100 milligrams, Xinhua had reported.
Above 200 milligrams is considered hazardous, with children more vulnerable to lead poisoning which can harm the nervous system.
It was not immediately clear how the children were poisoned but officials have been taking samples of groundwater, soil, air and sewage to check for contamination.
Residents who lived within 500 metres (yards) of the plant were supposed to have been relocated but so far only 156 families had been able to move to new homes, state media reported earlier this week.
The county government has begun building new homes for the 425 families still living next to the plant, Xinhua reported Friday.
The new homes located one kilometre from the factory are expected to be ready within two years.
"I'm ready to move, the earlier the better, as long as the new place has water, electricity and easier access to transport," Lu Tao, who lives 100 metres from the plant, was quoted as saying.
Many poverty-stricken regions in China's interior have introduced high-polluting industries without the necessary environmental evaluation, in a desperate bid to boost economic growth, state media has said.