Chinese prosecutors have successfully sued a county environmental agency for inadequately punishing a sewage firm that produced dye without appropriate safeguards – the first such public interest case against a government department.

The Supreme People’s Procuratorate, China’s top prosecutor, said prosecutors had successfully proved that an environmental protection department in Shandong province had committed “illegal acts” in its dealings with the Qingshun Chemical Technology Company.

The case was filed in December 2015 in the Qingyun county court, with such departments coming under increasing scrutiny amid growing public discontent over pollution.

In 2014 the sewage firm was found to have produced dye without adequate safeguards. But the environmental protection bureau in the county imposed only nominal administrative punishments and allowed the company to start trial operations, the court said.

The case was described by the Supreme People’s Procuratorate at the time as China’s first “administrative public interest litigation case” after the National People’s Congress had earlier authorised prosecutors to file such lawsuits in a pilot programme.

In 2015 China’s supreme court said it would give environmental groups the power to sue before any pollution had occurred if they could show that a particular activity could threaten the public interest.

The Chinese government has declared a “war on pollution”, vowing to abandon a decades-old model of growth at all costs that has spoiled much of China’s water, skies and soil, in response to public anger over environmental problems.