China moved on Friday to silence parents of victims of its tainted milk scandal, underscoring Beijing's determination to quell unauthorised action in response to social and economic problems.

Zhao Lianhai, the organiser of a network of parents whose children fell ill after consuming baby formula tainted with the industrial chemical melamine, was detained as his group prepared to lobby the government for continued free testing and treatment for their children and other victims.

The crackdown came after the health ministry said the scandal and the business of compensation was ‘in principle over'. Last week, a court declared the bankruptcy of Sanlu, one of the dairy companies at the heart of the scandal. Sanlu's former chief executive and some other accused officials are on trial for alleged breaches of the law.