Dozens of people living near a factory that makes batteries for motorcycles in Zhejiang province have been found to have dangerously high levels of lead in their blood, according to medical tests carried out since March.

A spokesman for Deqing county's information office confirmed that the people were from the Xinshi town area.

Zhejiang Haijiu Battery Co Ltd has been ordered to suspend its operations and the county government sent an investigation team to the company on Thursday to probe the lead poisoning, the spokesman said.

In Mengxi village, which is within the jurisdiction of Xinshi town, medical tests showed that 19 children, including a 5-month-old baby, were among those with excessive lead in their blood. The total number of people affected has not been made public and many more people are undergoing tests, according to Rong Weiguo, a worker at the factory for the past three years.

Rong's 4-year-old son and a nephew and niece are among those who were found to have high levels of lead in their systems. The three children all have at least 293 micrograms of lead per liter of blood, which far exceeds the normal level of 100 micrograms.

The three children were sent to a hospital in Shanghai on Wednesday for further tests and treatment, said Rong.

Some adults, including factory workers and villagers, have also been found with lead in their blood - the most severely affected person to date had 590 micrograms of lead per liter of blood, according to a worker surnamed Chen, who had 413 micrograms when he was tested on April 29.

Excessive amounts of lead in the blood can damage the digestive, nervous and reproductive systems and cause stomach aches, anemia and convulsions.

The county's environmental protection officials collected samples of soil, water, vegetables and grain from the area around the plant on April 30. The batches are being tested but the results have not yet been released.

The battery company's deputy general manager Zhao Guogen said: "It may have something to do with the fact that some workers did not take a shower and change their work clothes before leaving work but our company will foot the sick children's medical bills."

Haijiu Battery, which was founded in May 2003, mainly produces lead-acid batteries for motorcycles. It employs about 1,000 people and has an annual output of 9 million batteries.