Multiple Chinese departments, including the State Administration for Market Regulation, the Ministry of Industry and Information Technology, the National Health Commission, and the National Disease Control and Prevention Administration, have formed a joint investigation team to look into matters concerning alleged presence of formamide in infant diapers, vowing to handle the matter in accordance with laws and regulations, according to a post on the State Administration for Market Regulation's official website on Monday.

Relevant updates will be announced in due course, said the post.

The latest moves from multiple Chinese departments came after days of intense public concern triggered by an investigative report by the Beijing-based Economic Information Daily, a newspaper under the Xinhua News Agency on June 18, which said that certain diaper products made by Babycare, Huggies and Bibabebe had tested "positive" for formamide, a toxic substance.

Over the weekend, the controversy over alleged formamide contamination in baby diapers continued to escalate among customers especially parents, as Wang Wenzhi, the reporter who is behind an investigative report and caused a national whirlwind of concern, issued an open letter denying he was "making news", while the embroiled brands, Babycare and Huggies, called for the authorities to get involved and publicize an official testing result as soon as possible.

On Sunday evening, Wang came up with an open letter on his Sina Weibo account, explaining the background of his investigative report which he said was "backed up by a laboratory testing from Shandong Public Health Clinical Center," denying online claims that his "formamide-containing diaper" report was fabricated in order to promote "related equipment" for personal gain.

In the letter, Wang said that public attention since the story broke had drifted away from the "central issue" — "the source of the formamide found in children's bodies" — and instead focused on whether his report contained flaws or whether he was chasing online traffic.

Wang, in his letter, requested the relevant authorities to set up an investigation team to conduct a full-chain review of all the facts of the incident he has exposed. "I firmly believe a national-level investigation will clarify all the facts, eliminate potential risks, and provide millions of concerned parents with a definitive answer," Wang wrote.

Early Monday morning, Babycare issued a statement asking relevant government departments to release official diaper-testing results as soon as possible. The company also called on the authorities to conduct a comprehensive investigation into "where the formamide in children's bodies came from," saying the truth behind reports of excessive formamide levels found in children's blood samples from certain regions of the country should be fully probed and clarified.

Huggies' parent company, Kimberly-Clark China, posted a statement on its Weibo account on Sunday, saying that it had completed a review of its full product line and raw materials, with all results "meeting standards." The company said that it had requested independent sampling inspection by the regulators.

In the statement, Kimberly-Clark China asked relevant authorities and authoritative bodies to form a joint investigation team to examine key issues in the case, including testing standards, methods and samples, and, the company hoped that relevant government inspection agencies could publish their results promptly.

Some local market regulators have already stepped in. Authorities in Hangzhou, Huzhou, Shanghai, Nanjing and Tianjin have conducted inspections or sampling checks involving diapers made by the three brands, covering company sites, production links, raw materials and products on sale, according to media reports. No official test results had been released as of Monday.