Two kindergartners killed in Chinese school poisoning

Two children died and another 30 were sickened in a mass poisoning at a kindergarten in southwestern China, authorities said Friday.

Investigators identified the toxic substance as a powerful rat poison but did not yet know how it had been ingested Wednesday in the kindergarten in Yunnan province's rural Qiubei county, according to a statement from the provincial government.

It was unclear whether the poisoning was intentional or an accident.

Food served at the school, the Jiajia Kindergarten, has been tested and found to be safe, the statement said. The particular type of poison was outlawed years ago as a threat to human health, but it remains in circulation.

State broadcaster CCTV said that the school began accepting students last year despite not being fully licensed, a common problem in China's vast and largely impoverished hinterland.

Apart from the deceased victims, aged 4 and 5, another six children remained hospitalized while the others had been released and returned home.

Food safety has become a contentious issue in China, with a rising number of food-poisoning cases due in part to lax safety standards at small factories.

In 2008, melamine-tainted milk made in China killed six babies and sickened thousands. And last year the U.S. Food and Drug Administration investigated the deaths of almost 600 dogs that ate jerky treats made in China.

The same year, more than 12,000 pig carcasses were found floating in a Beijing waterway after suffering from a common virus, and in January, donkey meat sold at Walmart Stores in China was found to contain the DNA of other animals.

The FDA in 2013 cleared four Chinese poultry processors to ship meat to the United States, but only cooked meat from birds raised in the U.S. and Canada, The New York Times reported.

Al Jazeera and wire services