Anheuser-Busch and Miller Brewing Co. are set to be sued by an activist group in the US over their caffeinated alcoholic drinks.

The Center for Science in the Public Interest has said that drinks such as A-B's Bud Extra and Tilt and Miller's Sparks, contain stimulant additives that are "not officially approved for use in alcoholic drinks," referring to the beverages as "alcospeed".

The group said that the marketing of the drinks is designed to appeal to "young, and often underage, drinkers" and that it will seek a permanent injunction prohibiting the combination of stimulants with alcohol as well as suggest that all profits from the drinks should be donated to charity.

CSPI's alcohol policies project director George Hacker said: "This is just the latest and one of the more sinister attempts by alcohol producers to prey on a new generation of future problem drinkers. This is an industry that wants its consumers young and it wants them hooked. And alcospeed contains two addictive ingredients in one sunny container, and several other stimulants that are not even approved for use."

Last month, A-B and Miller were hit with subpoenas from attorneys general in the US over their sales and marketing of their caffeinated alcoholic drinks brands. A-B said at the time that it is cooperating with the subpoenas, noting that the formation and labelling for its Tilt and Bud Extra brands had already been approved by federal authorities prior to the subpoena being issued.

CSPI's letters to A-B and Miller urge the companies to negotiate a settlement without resorting to litigation, giving the companies 30 days to make a decision.

No-one from A-B or Miller was immediately available for comment when contacted by just-drinks today.