SHANGHAI - China on Wednesday said it was investigating reports that toothpaste containing a potentially deadly chemical had been exported to Central America.

Pet food ingredients from China tainted with the mildly toxic chemical melamine were blamed in the deaths of dogs and cats in North America earlier this year, prompting a massive pet food recall and, eventually, an investigation in China.

A joint task force involving customs and the State Food and Drug Administration had been formed to investigate the toothpaste contamination reports, the main food safety regulator, the General Administration of Quality Supervision, Inspection and Quarantine, said it in a statement on its Web site.

It said investigators were pursuing leads in both Beijing and the eastern province of Jiangsu.

"The Chinese government has always placed a heavy importance of food and drug safety," the statement said. It said investigators would clarify the situation and apportion responsibility, and would announce their results as soon as they could be obtained.

On Tuesday, US Labor Secretary Elaine Chao said Chinese officials told her they would fully investigate any problems discovered in Chinese food exports.

Wednesday's statement didn't say what companies were being checked into, although the general manager of a company based in Jiangsu _ Danyang Chengshi Household Chemical Co. _ said Tuesday he was being questioned by investigators.

Chen Yaozu said he had exported toothpaste containing small amounts of diethylene glycol to Panama _ later shipped to the Dominican Republic _ but said that was permitted under Chinese rules and did not pose a direct health risk. Diethylene glycol is primarily used to keep toothpaste moist.

China's Cabinet earlier this month ordered a thorough crackdown against unsafe practices in the food industry.