Lawyers for nearly 100 families whose children were sickened by tainted milk decided Thursday to go ahead with a class-action lawsuit, hoping to pressure Chinese authorities still dithering over compensation.

The lawsuit against state-owned Shijiazhuang Sanlu Group Co., the dairy at the center of China's worst food safety crisis in years, seeks medical and other expenses, payments for trauma and compensation for the families of those who died.

The move marks a significant uptick in confrontation between the families and the government.