SHANGHAI — Three Shanghai dairy executives have been sentenced to jail after milk products their company made were found to be tainted with an industrial chemical at the center of China's milk safety scandal.

Shanghai Panda Dairy Co. was forced to close last year when unacceptably high levels of melamine, which can cause kidney stones or failure, were found in milk powder and condensed milk. Some Shanghai Panda products contained more than 34 milligrams of melamine per kilogram, well over the legal limit of 2.5 milligrams.

Fengxian District Court official Yang Xuelong confirmed today that the three executives were sentenced to jail terms of three to five years. He would not comment further.

In 2008, the discovery of widespread melamine contamination of milk, baby formula and other dairy products prompted an overhaul of China's entire dairy industry. At least six children died after drinking contaminated baby formula and more than 300,000 were sickened.

New cases appeared last year, some of it from old batches that weren't destroyed after the 2008 scandal, underscoring the difficulties China faces in improving food safety.