China's state-run media are reporting that prosecutors have charged six men with making and selling the chemical at the center of the country's tainted milk scandal.
The official Xinhua news agency said the trials opened Friday in four courts in northern Hebei province.
Xinhua reports that prosecutors say a cattle farmer named Zhang Yujun in Quzhou County concocted hundreds of tons of a so-called "protein powder" made of melamine and malt starch. They say one of his neighbors bought and resold the powder.
Four other men - Zhang Heshe, Zhang Taizhen, Yang Jingmin, and Gu Guoping - in Wuji county are accused of adding the powder to raw milk and selling the tainted milk to the Sanlu dairy giant.
Sanlu was the first milk manufacturer found to be selling products tainted with melamine when the scandal surfaced in September. The company declared itself bankrupt earlier this week.
Tainted milk from Sanlu and some 20 other Chinese companies sickened nearly 300,000 children and killed six.
Many families are seeking to bring the responsible companies to trial, but say the courts are blocking their petitions.
Some information for this report was provided by AFP and AP.