A PMI spokesperson said in an emailed statement: “Preventing children from smoking is of the highest priority and we take every possible action to ensure that children are not exposed to the marketing or sale of tobacco products,” and added that it has policies in place to make sure that its marketing is directed only toward adult smokers. PMI said that it trains retailers to make sure they are aware of underage regulations and their role in preventing the sale of tobacco products to minors.

BAT cigarette brands are smoked by about one in eight of the world’s one billion adult smokers, according to the company’s website. It is developing “potentially less risky” products, such as Glo cigarettes, which are heated up by an iPod-sized device to a lower temperature than with regular cigarettes, reducing the tar and toxins in the smoke.

A spokesperson said in an emailed statement: “Our products are for adult smokers only and that under-age smokers are not, and will never be, our target audience, anywhere in the world,” adding that it provides posters to retailers with a message that it does not sell to people who are under age.

BAT added that it has strict rules to ensure outdoor advertising is not seen within 100m of a school and that its marketing principles ensure that products are marketed responsibly in the 200 markets where it operates.

A spokesperson from Imperial said in a statement emailed to CNBC: “We sell our brands in markets where there’s a legitimate and existing demand for tobacco products and take the same responsible approach in places like Africa and Asia as we do in any other territory.

“For us, responsible marketing is about ensuring that our product and brand communications are not aimed at, or made appealing to, people under the age of 18 or non-smokers and that we operate in accordance with local laws.” The spokesperson added that Imperial also has its own international marketing standard.

A JTI spokesperson said it complies with all laws regarding advertising of tobacco products and that it does not market products to minors. “This is best achieved by prevention schemes in shops, for example a minimum purchase or sell-to age, proof of age schemes, negative licensing and fines for retailers and proxy purchasing,” the spokesperson added.

The Campaign for Tobacco Free Kids published 27 reports from country investigations that were produced in 2016. It worked with organizations including Johns Hopkins Bloomberg School, public health groups and non-governmental organizations and countries included Argentina, Bangladesh, Benin, Bolivia, Bosnia and Herzegovina, Burkina Faso, Cameroon, Georgia, India, Indonesia, Kenya, Moldova, Nicaragua, Nigeria, Pakistan, Peru, Romania, South Africa, Switzerland, Uganda and Ukraine.