Background Tobacco companies’ intentions to influence the WHO Framework Convention on Tobacco Control (FCTC) via the Conference of Parties (COP; the official biannual meeting where Parties review the Convention) are well documented. We aimed to analyse Twitter data to gain insights into tobacco industry tactics, arguments and allies.

Methods We retrieved 9089 tweets that included #COP8FCTC between 1 and 9 October 2018. We categorised the tweets’ content and sentiment through manual coding and machine learning. We used an investigative procedure using publicly available information to categorise the most active Twitter users and investigate tobacco industry links. Network analysis was used to visualise interactions and detect communities.

Results Most tweets were about next-generation products (NGPs) or ‘harm reduction’ (54%) and tended to argue in support of NGPs; around one-quarter were critical of tobacco control (24%). The largest proportion of most active tweeters were NGP advocates, and slightly over half of those had either links to the Philip Morris International (PMI) funded Foundation for a Smoke-Free World (FSFW) and/or to the International Network of Nicotine Consumer Organisations, a network to whom the FSFW granted US$100 300 in 2018. PMI was the most active transnational tobacco company during COP8.

Conclusions The nature of the activity on Twitter around COP8, including a substantial online presence by PMI executives and NGP advocates with links to organisations funded directly and indirectly by PMI, is highly consistent with PMI’s 2014 corporate affairs strategy, which described engaging tobacco harm reduction advocates to ‘amplify and leverage the debate on harm reduction’ around events such as the COP.