The experiments - reported by the Independent newspaper on Thursday, in turn citing specialist journal Food and Chemical Toxicology - were condemned by anti-smoking campaigners as an apparent attempt to make tobacco more appealing to young people.
Among the flavourings tested by BAT, whose brands include Kent, Dunhill, Lucky Strike and Pall Mall, were chocolate, wine, sherry, cherry juice and vanilla, the newspaper said.
British anti-tobacco lobby Action on Smoking and Health, or ASH, reacted with fury, labelling the tests "appalling".
Aimed at kids?
"These are just the sort of ingredients that could make cigarettes more attractive to children. Why would they want to test these sort of additives?" ASH director Deborah Arnold told the paper.
In the trials, 482 different flavours were tested out on laboratory rats in Canada - tobacco tests on live animals are banned in Britain - to see if the additives had any different impact on health than ordinary cigarettes.
A BAT spokesman told the Independent that tiny quantities of some flavourings such as cocoa butter were already used in certain brands.
These had been included for years but the amounts were so small that smokers could not detect them, he said, dismissing the notion that the company aimed to attract children with new flavourings.
"Anybody who might attempt to claim that they are added to appeal to youth are barking mad because cigarettes taste like cigarettes," he said.