The ‘No, Prime Minister’ ad is the latest strand of Forest’s ongoing Hands Off Our Packs campaign, which was launched in February 2012 to lobby against the introduction of plain cigarette packaging.
It links to a microsite where opponents of plain packaging can enter their contact details to have a letter sent in their name to the Prime Minister.
Simon Clark, director of Forest, said: "One of the reasons we’ve revamped the campaign to specifically target David Cameron is because he appears to be the person who’s going to make the final decision on this – it seem to be out of the hands of the Department of Health."
The letter calls on Cameron to wait until the Government has studied the impact of the tobacco display ban, which will not be fully implemented until 2015, and the introduction of larger health warnings, which are being introduced in 2016 as part of the EU's revised Tobacco Products Directive.
The online ad campaign will run for 72 hours and will have total exposure on websites and blogs including Guido Fawkes, ConservativeHome, Labour List, Liberal Democrat Voice, Left Foot Forward, UK Polling Report, Political Betting and Newsbiscuit.
Clark said: "We have two principle target audiences, one being the Government itself and all of the political advisers around No.10 and the second being consumers themselves, because we want them to voice their opposition to plain packaging.
"The whole area of plain packaging is quite a dry subject, so we’re trying to get across to the consumer what the implications could be in terms of once you remove branding from cigarettes, next it could be alcohol and then sugary drinks – anything will be up for grabs."
He added that Forest had succeeded in its initial campaign in the build-up to the four-month consultation on plain packaging in 2012, resulting in 427,888 of the 665,000 responses being opposed to the policy.
However, after initially putting the idea to one side, the Government is now gearing up to announce regulations for plain packaging.
Clark said: "This is one of our messages – that if you’re going to have a consultation and then ignore the result, that brings the whole democratic system into disrepute."
He added that the consumer rights group would follow its online ad campaign with a printed advertising campaign, most likely once the new regulations are announced.
Forest is supported by British American Tobacco, Imperial Tobacco Limited and Gallaher (a member of the Japan Tobacco Group), although Clark said their relationship was "very much arms-length support".
"We do most of our PR and lobbying in-house, where we do have a fair bit of PR expertise – we work to a very limited budget and we don’t have access to [the tobacco companies'] in-house PR teams."