China said Wednesday that it has detained 202 people for their role in an out-of-date immunisations scandal that has fuelled public outrage.

It is the latest health and safety scandal to emerge in China, where 300,000 children fell ill, six of them dying, in a notorious 2008 case involving milk powder contaminated with melamine.

The immunisations case involves the illegal and improper storage, transport and sale of tens of millions of dollars' worth of vaccines -- many of them expired -- reports say.

The State Council, China's cabinet, said 357 government officials have also been fired or demoted in connection with the scandal, according to a statement on its website.

Premier Li Keqiang heard a report on the progress of investigations into the matter during a regular meeting of the group, it said.

Public fury erupted over authorities' delay in publicising the case, which only came to light last month despite the two key suspects, a mother and daughter from Shandong province in eastern China, being arrested in April 2015.

From 2010, the two main suspects illegally sold 25 different kinds of expired or improperly stored vaccines worth more than 570 million yuan ($88 million), the official Xinhua news agency reported previously.

They included shots for polio, rabies, hepatitis B and flu for both children and adults, Caijing magazine said, citing drug safety officials.