Tobacco giant Philip Morris International has been lobbying federal government MPs to overturn Australia’s ban on vaping, but its efforts remain hidden from public view due to fundamental flaws in the lobbyist oversight regime.

Philip Morris, owner of six of the world’s 15 biggest cigarette brands, is in the midst of a significant push to grow global sales of its vaping products, predicting they will bring in $17bn to $19bn by 2025, roughly 42% of its total revenue.

But the company’s plan has been hampered in Australia by the federal government’s effective ban on nicotine e-cigarettes.

Guardian Australia understands Philip Morris has been seeking meetings with Coalition MPs as part of its bid to overturn the vaping ban. Some within government have refused to meet with the company.

At the same time, Philip Morris has placed prominent ads on page three of both the Australian and the Australian Financial Review, calling for staff to help it achieve a “future without cigarettes” and a “smoke-free Australia”. Tobacco advertisements are banned under Australian law, but Philip Morris appears to have relied on an exemption allowing job ads.

In a statement, Philip Morris Australia confirmed it was engaging with “a wide range of stakeholders, including government officials across various political parties” on various issues, including the vaping ban. It said it was seeking to discuss “why the millions of Australians who smoke deserve access to better alternatives than cigarettes”.

The fact that Philip Morris is attempting to lobby politicians has been completely hidden from the general public. Philip Morris appears nowhere on Australia’s lobbyist register – the public’s only window into the world of lobbying – because of fundamental flaws with the system. Australia does not require companies such as Philip Morris to register if they use people from within their own company to lobby government.

Only third-party lobbyists – consultants who lobby government on behalf of a private interest – are required to declare themselves and their clients to the public.

Quick Guide Political lobbying in Australia: the basics Show What do lobbyists do? Lobbyists attempt to influence government policy or decisions on behalf of either a client or their own organisation. Ethical lobbying is a valuable and important element of a healthy democracy. It helps those who have a stake in government policy to convey their views and expertise. There are two broad types of lobbyists: third-party lobbyists, who are engaged as consultants; in-house lobbyists, who work directly for corporations or interest groups. Who hires lobbyists? For many Australians, lobbying conjures images of powerful corporations working to sway politicians behind the scenes. There is a truth in that. The big banks, mining and energy giants, pharmaceutical companies, casinos, Amazon, Google and Facebook all engage lobbyists. But lobbyists also work on behalf of not-for-profits and community groups, including for veterans, social workers, aged-care staff, school principals and environmental organisations. What is the lobbyist register? The lobbyist register is the public's only window into the world of lobbying. It's a publicly available online list of lobbying firms, individual lobbyists and their clients. The register was a huge step forward when it was introduced in 2008, but remains frustratingly opaque. It doesn't tell us who is lobbying whom, about what, or when. Compare that with the ACT, where lobbyists are required to file quarterly reports on their activities, or NSW, where ministers are required to publish their diaries. The federal register is also completely blind to the activities of in-house lobbyists. What is the lobbyist code of conduct? The code tells lobbyists how they must behave when approaching the government and is designed to maintain ethical standards. But the code is not legislated and has no real teeth. It goes largely unenforced and the punishments are weak. The worst sanction available to authorities is removing a lobbyist from the register. The US and Canada have fines or jail terms for law breaches. Who keeps an eye on lobbyists? Federally it's the prime minister's department that loosely oversees lobbying. It takes on a largely administrative role, rather than an investigative or regulatory one. Its core job is to maintain the register and communicate the code's requirements to lobbyists. It lacks independence, relies on reports of bad lobbying and rarely, if ever, takes enforcement action.

Philip Morris’s managing director, Tammy Chan, said the company directly engaged with government officials. She said Philip Morris was not required to list itself on the lobbyist register.

Guardian Australia understands the company also engages former senior government officials, including one who is a registered lobbyist for other companies.

But Chan said such individuals were providing advice only, not lobbying on the company’s behalf.

“There is therefore no requirement to register on the federal Register of Lobbyists,” she said.

The Coalition last month agreed to set up an independent inquiry into the health impacts of nicotine e-cigarettes, following a concerted push to overturn the ban from within its own ranks.

The office of the health minister, Greg Hunt, said he had not met with Philip Morris on the vaping ban.

It is legal in Australia to buy vaping devices. But nicotine is classed as a poison and it is generally not legal to possess, use, or sell devices containing the chemical.

The Therapeutic Goods Administration rejected a bid to exempt nicotine as a dangerous poison last year, and the Standing Committee on Health, Aged Care and Sport found earlier this year that the regulatory framework was suitable, and more research on e-cigarettes was needed.

A spokesman said Hunt “strongly supports” the TGA’s current position on the sale of nicotine used in e-cigarettes.

“The overwhelming medical advice and evidence is that it’s likely to lead to the uptake of smoking and we cannot support that,” the spokesman said.

“This is the view of the TGA, Australia’s chief medical officer, chief health officers from all Australian states and territories and the National Health and Medical Research Council (NHMRC).”

Proponents of e-cigarettes argue they are a less harmful alternative to standard combustible cigarettes and can be used as a quitting aid. Drug law reform advocate Alex Wodak said Australia’s smoking rates had flatlined in recent years, and increased slightly in NSW.

He said nations such as Japan, the United Kingdom, the United States, and Canada, where vaping was allowed, were seeing continued reductions in their smoking rates.

“Everywhere where tobacco harm reduction is taken seriously, and where reduced risk products have been made available and it’s being made easy for people to obtain, smoking rates have fallen more rapidly than they ever have before,” Wodak told Guardian Australia.

But both the NHMRC and the Royal Australian College of General Practitioners say the effects of e-cigarettes are not yet fully known.

“Electronic cigarettes … are often marketed as a method to assist smokers to quit, or as a ‘safe alternative’ to conventional tobacco cigarettes,” the NHMRC said in a statement last year. “However, there is currently insufficient evidence to support claims that e-cigarettes are safe and further research is needed to enable the long-term safety, quality and efficacy of e-cigarettes to be assessed.”

The Australian Medical Association has also warned against legalising vaping bans. The AMA has warned e-cigarettes were being “aggressively” pushed by tobacco companies to maintain or establish a nicotine addiction in users.

• This reporting is supported by the Susan McKinnon Foundation through the Guardian Civic Journalism Trust