BEIJING - The parents of a Chinese infant allegedly sickened by tainted baby formula have launched what could be the first lawsuit in the nation's escalating milk scandal, their lawyer said Wednesday.

Ji Cheng, a partner from the Deheng Law Office in Beijing, told AFP he had recently filed the suit against milk producer Sanlu Group at the Zhenping County Court in central China's Henan province.

"We handed over all the documents to the court, and now we're waiting for a reply," he said.

The infant, identified in the local media as a one-year-old boy from Zhenping county, started drinking Sanlu powdered milk shortly after his birth in July last year.

He was diagnosed with a kidney stone this summer, allegedly due to melamine mixed into the milk powder, and has since been hospitalised, most recently in Beijing.

The parents of the boy are demanding 150,000 yuan (22,000 dollars) in compensation from Sanlu Group, according to Ji.

"I believe the figure of 150,000 yuan is reasonable," he said, citing the medical costs paid by the parents in the weeks since their child was admitted to hospital for emergency treatment.

The tainted milk scandal has sent shockwaves through China's dairy industry, following the discovery that melamine killed four children and sickened 53,000.

The scandal continues to escalate, as a growing number of companies have pulled their China-made products off shelves in overseas markets.

- AFP/ir