A vaccine scandal in China has caused widespread outrage both on social media and in the pages of the country's government-controlled newspapers, with officials slamming the company responsible and calling for a full investigation.

Key points:

• Changsheng fabricated production records and product inspection records of a rabies vaccine
• It was also fined over substandard production of diphtheria, whooping and tetanus vaccines
• The company was found to have sold more than 250,000 ineffective DPT vaccines

The controversy kicked off a week ago, when China's regulator announced that vaccine manufacturer Changsheng Biotechnology had violated standards in the production of a rabies vaccine.

The China Food and Drug Administration said in a statement that during an inspection on Monday, it found Changsheng fabricated production records and product inspection records, and arbitrarily changed process parameters and equipment.

The regulator ordered the company, which is China's second largest maker of rabies vaccine, to halt production and recall all of its products.

Public concern intensified when authorities revealed on Friday they were fining the same company over substandard production of diphtheria, whooping cough and tetanus (DPT) vaccines, something uncovered last November.

The company was found to have sold more than 250,000 ineffective DPT vaccines, administered to children as young as three months old.

In a statement on Sunday, Chinese Premier Li Keqiang said the company had crossed a moral red line and urged severe punishment for the companies and people implicated.

"We will resolutely crack down on illegal and criminal acts that endanger the safety of peoples' lives," he said.

"[We will] resolutely punish lawbreakers according to the law, and resolutely and severely criticise dereliction of duty in supervision."

In 2016 more than 200 people were arrested after it was discovered that tens of millions of dollars worth of expired vaccines had been sold around the country for years.