"The Commerce Commission is aware of the concerns raised in the media about the Miracle Mineral Solution and is assessing whether the claims the company is making in promoting and selling this product may breach the Fair Trading Act."
The commission could ask the non-religious church, which has its headquarters in the Dominican Republic, to prove the claims are true.
If it found the claims misleading and a breach under the act, the commission could prosecute, the penalties for which included fines of up to $600,000 for a group and $200,000 for an individual, and injunctions to stop the 125ml bottles being sold.
New Zealand's medical regulatory body, Medsafe, has followed the lead of the US Drug and Food Administration and the UK Food Standards Authority in urging people to avoid MMS.
"These products, when used as directed, produce an industrial bleach that can cause serious harm to health," Medsafe said.
Medsafe had not received any formal complaints about the product.
However, the Ministry of Health said Medsafe's investigations staff had visited the company operating the website used to sell MMS and associated products.
"Information on the website about the seminar and the arrangements for supply of any product is being assessed with a view to taking further regulatory action if an offence has been committed.
"It is unlawful to advertise or sell a product for which therapeutic claims are being made unless it has first been approved through the assessment process provided for by the Medicines Act 1981."
Potential penalties included a fine of up to $100,000 for a company, and $20,000 or up to six months' imprisonment for an individual.
Meanwhile, police said they would follow up any health complaints related to the product forwarded to them from the Ministry of Health.
About 50 people attended a $646-a-head, three-day seminar on the product that began in Ngatea yesterday, where church leader Jim Humble and member Mark Denon gave talks on MMS.
Hosted by Roger Blake at the Ngatea Water Gardens Function Centre, the audience were also taught how to start their own chapters of the church.
Solution user: I am happy to pay $646 to seek the truth