The Charity Commission is looking into a south London-based church after it was accused of promoting false coronavirus cleansing products made of oil and string.
The Charity Commission in turn opened a regulatory compliance case into Kingdom Church GB.
Kingdom Church GB denied that it promoted or sold the equipment, but said it was instead sold by a separate company.
The NSS said in a statement that the company was run by a trustee of the church.
The church also promoted the product on its website, the NSS said, although a link to the product has allegedly now been deactivated.
A statement from the NSS said: "Selling bogus protection kits during the current crisis is worse than useless; it's exploitative and potentially harmful.
A spokesman for the church said the cleansing kit highlighted by the NSS was owned by a separate company, but accepted that the trustee was involved in the company.
But he said the church did not promote or sell the product.
The company’s website says that the “articles and its opinion on this website is solely under Bishop Climate Ministries and not the Kingdom Church”.
A Charity Commission spokeswoman said: “We are looking into the serious concern about Kingdom Church GB’s alleged sale of false Covid-19 protection devices as a matter of urgency.
“We have opened a regulatory compliance case to assess the matter and will be liaising as appropriate with other agencies.
“Charity can and should lead the way in taking public expectations seriously and charity leaders should demonstrate high standards of conduct and behaviour.”