Nigel Farage’s group campaigning against the World Health Organization (WHO) is staffed by consultants who work with the nicotine products industry, the Guardian can reveal.

Farage is the chair and a co-founder of Action on World Health, which campaigns to reform or replace the WHO, arguing that it should not be putting pressure on governments to bring in public health measures.

The other co-founder is David Roach, whose firm provides secretariat services to the Global Initiative on Novel Nicotine, which advocates for nicotine pouches and other products. Roach’s firm has also lobbied in the past year on behalf of a vaping company called ANDS.

In the Action on World Health “manifesto”, released before the UK election, it opposed “excessive regulation” on vaping. It said: “Adults should be treated like adults, instead of the WHO bullying countries into treating its citizens like children through excessive regulations on food, alcohol, fizzy drinks, and vaping products that are 95% less harmful than smoking.”

Farage launched the group in May, and his role at the organisation does not appear on the MPs’ register of interests. It is understood Farage has made a late declaration to the register in recent weeks, but it has not yet appeared publicly.

His spokesperson had no comment on the group’s links to consultants working with the novel nicotine industry, which were uncovered jointly with the Good Law Project.

The spokesperson said: “Nigel Farage is not paid in his role at Action on World Health. He is chairman of the organisation because he has long believed that the WHO is bloated, undemocratic and a complete catastrophe.”

Roach is the campaign director of Action on World Health, and two more of his staff members from his company, David Roach Consulting, are listed as working for the organisation.

Asked about his clients, Roach said no vaping or novel nicotine companies were providing funding to Action on World Health, and that David Roach Consulting was not being paid for its services to the organisation. He said Action on World Health did not have a public list of funders because that would breach confidentiality.

Asked whether it should be transparently declared by Action on World Health that David Roach Consulting was participating in a campaign against the WHO while having had clients in the vaping and nicotine industry, Roach said: “We do not currently work with any vaping companies, but I imagine most novel nicotine companies would support AWH’s aims to reform or replace the WHO given its misguided approach to reduced-risk products.”

He added: “Action on World Health (AWH) is an international campaign group committed to reform all aspects of WHO activities. Health policies which infringe on national sovereignty should be under the control of nation states, not unelected global bodies. It should not dictate or put pressure on governments to implement public health measures which interfere with domestic policies; and rather than pushing for one-size-fits-all treaties and mandates, the WHO should instead be mandated to advise and facilitate international cooperation.

“We need a complete review of the WHO with a focus on taking back control of national public health in areas where it continually overreaches.”

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Jo Maugham, the director of the Good Law Project, said campaign groups without transparency around their funding should be treated with scepticism about who was financing them. He said “social media influencers selling toasters” had to declare any hidden funders, so “the law really should treat the sale of political ideas in the same way”.

The WHO has accused Action on World Health of spreading misinformation about its international treaty designed to improve global pandemic preparedness.

WHO member states are negotiating a deal to shore up cooperation against new pathogens. If adopted, the legally binding treaty would commit countries to helping each other in the event of a pandemic, increase research and sharing of data, and promote fair access to vaccines.

Responding to Action on World Health’s claims, a spokesperson said a draft of the treaty reaffirmed “the principle of sovereignty” of member states.

“Claims that the draft agreement will cede sovereignty to WHO and will give the WHO secretariat power to impose lockdowns or vaccine mandates on countries are false and have never been requested nor proposed,” they said. “This agreement will not, and cannot, grant sovereignty to WHO.”