Gladys Kessler, the Washington federal judge, ordered on Thursday a ban from January on the use of terms such as "light", "low tar" and "mild" on cigarette packets.

Kessler also ordered the firms to take out advertisements on national television and in newspapers to spell out the truth about smoking that they sought so long to hide.

But she prompted an outcry from campaigners by rejecting government demands for "Big Tobacco" to fund a $10bn stop-smoking campaign. Nor did she agree to forbid cigarette advertising in motor sports.

Nevertheless, Kessler endorsed the government's central argument that the tobacco giants had systematically tried to distort the fact that smoking kills.

"Despite internal recognition of this fact, defendants have publicly denied, distorted and minimised the hazards of smoking for decades," she ruled in a 1,683-page opinion issued at the end of a two-year trial.

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One of the defendants, Philip Morris's parent Altria Group, said it would appeal on the grounds that much of Kessler's decision was not supported by the law and appeared to be "constitutionally impermissible".

The other defendants were American Tobacco, British American Tobacco, Brown and Williamson Tobacco, Lorillard Tobacco and RJ Reynolds Tobacco.

The department of justice said it was "pleased with the court's finding of liability on the part of the defendants, but disappointed that the court did not impose all of the remedies sought by the government".
  
"Nevertheless, we are hopeful that the remedies that were imposed by the court can have a significant, positive impact on the health of the American public," it said in a brief statement.

The Campaign For Tobacco-Free Kids said the industry was "guilty as charged - guilty of lying to the American people and marketing their deadly and addictive products to our children at untold cost in lives and suffering".
 
But the group urged the government to appeal for stricter  constraints on the industry's future conduct.
  
The American Heart Association said tobacco firms' "misdeeds have finally been exposed", but complained that Kessler's remedies amounted to no more than "a slap on the wrist".