Scottish micro-brewer BrewDog has threatened industry watchdog Portman Group with legal action over claims that it is "profiteering from the scourge of illegal drugs, mocking the misery caused by misuse".
The running battle between the two reached fever-pitch when Portman banned its Speedball beer last month, claiming it was associated with illicit drugs.
Portman said Speedball is the name given to the potentially lethal practice of combining heroin and crack cocaine to give both sedative and stimulant effects.
But BrewDog claims it released the beer in August to deliberately provoke Portman after it investigated, but later cleared, its three best selling beers — Riptide, Punk IPA and Hop Rocker.
It has now warned it will start defamation action unless Portman retracts its comments. A letter to Portman from BrewDog's solicitors said: "The allegations that our clients profit from illegal drugs and mock the misery caused by the misuse (or use) of illegal drugs are untrue and factually inaccurate."
BrewDog, which has reverted the name of Speedball to Dogma, has demanded that Portman chief executive David Poley write a formal apology, remove the words complained of from its press release on its website, undertake to not repeat the words in the future, pay a reasonable proportion of its legal costs and make a donation to an alcohol charity of £500.
Portman's Poley said: "Brewdog are trying to gag us from criticising this grossly irresponsible product.
"Most people will be appalled at their crass attempt to market a drink using the theme of illegal drugs. Instead of wasting time on futile legal action, they should concentrate on promoting those drinks we've not banned."