Shareholders in Hansen Natural have launched a lawsuit against the US soft drinks group, alleging that the company has broken the country's securities laws.

The lawsuit, filed in California late last week, claims that, over a five-year period, Hansen issued positive press statements and quarterly financial reports that were "materially false and misleading".

The suit lists claims including that Hansen failed to tell shareholders that it back-dated share options to some of its executives and that it lacked "adequate internal controls" to ascertain its "true financial condition".

Hansen, whose products include energy drink Monster, said the suit is "without merit" and that it would "vigorously defend" itself against the claims.

The company would, it added, file a motion to dismiss the complaint "at an appropriate time".