NEWARK, FEB. 18 -- The jury in a smoker-death trial was told today that Kinsley V. Dey Jr., the top officer of Liggett Group Inc. for the past decade, said the company didn't market its safer cigarette for fear that all other cigarettes would be implicated as harmful.

The witness was Joel Robinson of Brookline, Mass., the inventor of a device that he said increases fuel economy in automobiles. Testifying for plaintiff Antonio Cipollone, whose wife died of lung cancer, Robinson said that a Liggett executive had bought 24 of his devices for company vehicles.

He said that Liggett's "great success" with the device led it to arrange for Robinson to meet Dey and two unidentified Liggett officials in a Newton, Mass., hotel in September 1985. He said the meeting was to discuss the possibility of Liggett marketing the device.

To enhance the burning of gasoline, Robinson testified, the device uses the heavy metal platinum as a catalyst, just as the safer cigarette used palladium to improve the burning of tobacco.

In tests with condensed smoke done for Liggett by Arthur D. Little Inc., the palladium cigarette lowered skin cancers in mice by up to 100 percent compared with cigarettes not containing the heavy metal.

According to Robinson, the apparently similar roles played by the two catalysts led Dey -- "quite unexpectedly" -- to introduce the subject of the palladium cigarette.

The witness told the plaintiff's lawyer, Marc Z. Edell, that he asked Dey why Liggett had never produced or sold the palladium cigarette. He quoted Dey as replying, "To market such a cigarette to the public would in effect make the statement that all other cigarettes are harmful."

In cross-examination, Liggett attorney James V. Kearney sought to cast doubt on Robinson's claims for the device, partly by citing a letter in which Dey told the witness that Liggett couldn't find "satisfactory support from our viewpoint" to justify marketing it.

Earlier, the jury heard a reading of a deposition taken from Dey, who became president and chief executive of Liggett in December 1987.

Edell asked whether Edell had testified that, as president, he had "never spoken to any medical person {about} the causal relationship between cigarette smoking and cancer."

"That's correct," Dey replied. Did the executive rely on "just attorneys?" Edell asked. "Yes," Dey said.

Dey insisted that the purpose of Little's research was only "to try to reduce tumors formed from smoke condensate on the backs of mice."

Edell asked: "It had nothing to do with the health and welfare of human beings, is that correct?"

"That's correct," Dey testified.

Edell asked if Liggett had spent about $14.5 million on research "to save mice the problem of developing tumors; is that correct?"

"I have stated what we did," Dey said. "It has never been proven that you can extrapolate from mice to man."

Dey also testified that:

He does not believe some people become dependent on cigarettes, either psychologically or physiologically, and that he has never known a person who had wanted to stop smoking but was unable to do so.

He has read no literature suggesting smoking can cause a dependence, and has never discussed the issue with a physician or scientist.

Repeatedly, Dey testified that his and Liggett's position was that it had not been "established" that smoking caused lung cancer.