The poster, which reads 'Bacardi & Diet Cola. 0 sugar. 0 carbs. 52 calories', could fall foul of a grey area in Ofcom regulations on alcohol advertising, which states that while alcohol ads can contain factual statements about product contents, including comparisons, they must not make health, fitness or weight-control claims.
A spokeswoman for the ASA said that while it had so far received no complaints about the poster, Bacardi may have a case to answer.
Alcohol Concern branded the ad irresponsible. 'I think there is something slightly disturbing about selling an alcoholic drink as a dietary aid,' said a spokesman.
The ad, which was created in the US and adapted in-house by Bacardi for the UK, contains small print which states that the information is based on a 25ml measure of Bacardi Blanca Rum, containing 51 calories, 0g carbs, 0g protein and 0g fat, and a 200ml serving of a leading diet cola brand containing one calorie.
No one at Bacardi-Martini was available for comment.