The government received complaints from parents about Sanlu milk powder in June but no action was taken to investigate, mainland media reported.
An inquiry from the public about the product was found on the official website of the General Administration of Quality Supervision, Inspection and Quarantine on June 30, the Nanfang Daily reported.
The content of the inquiry was censored, but the follow-up messages could still be read yesterday.
The inspection administration said it would investigate only if more information could be provided.
The semi-official China News Service also reported that many parents of sick infants had complained to their local inspection administrations and even sent samples for testing. However, they were told that the powder met national safety standards, CNS reported.
Legal Weekly said it started investigating the scandal more than a month ago, but Sanlu presented two certificates from the inspection administration that its products met safety standards. Sanlu representatives interviewed by the weekly also denied the renal failures of infants were related to their products.
Mainland journalists said the first report about the scandal was aired by the metropolitan channel of Hunan cable TV in July after an unusually high number of kidney-stone cases among infants were found in a children's hospital.
However, the media have been low-key regarding the scandal as they dare not challenge Sanlu, a powerful state-owned enterprise, a mainland journalist said.
But the attention on the internet became too great to keep the story under wraps. According to the Legal Weekly report, a doctor puzzled by the cluster of unusual cases in his hospital blogged about his queries. The doctor concluded that Sanlu milk powder was responsible after he talked to other hospitals.
A baby's mother also posted her doubts on an online forum, which prompted the Legal Weekly journalist to investigate.
No media report was found during the Olympics as food-safety stories were banned in directives given to media by the Communist Party's propaganda department, but stories about the tainted milk powder started to emerge this week.
Sanlu at first said renal problems had nothing to do with its products, but on Thursday said the products were tainted. Yesterday, it admitted melamine was added, but blamed farmers for breaking the law.