NEWARK, FEB. 3 -- Liggett Group Inc. didn't tell the public for seven years about tests in 1955 showing that tars in four brands of cigarettes -- including its own Chesterfields and L&Ms -- had caused cancer in animals, an expert witness for the plaintiff in a smoker-death lawsuit testified today.

When Arthur D. Little Inc., the consulting firm that did the tests for the Liggett & Myers subsidiary, reported the test results in 1962, neither the sponsor nor the brands was identified, according to the testimony of Dr. Jeffrey E. Harris, the first witness for the widower of Rose D. Cipollone. In addition, Harris testified, neither Liggett nor Little has ever revealed that supplemental Liggett testing further incriminated certain ingredients of tobacco smoke as carcinogens.

The series of events was described in Liggett and Little internal documents introduced as evidence in connection with the testimony of Harris, a physician and health economist who teaches at Harvard Medical School and the Massachusetts Institute of Technology.

"I would have recommended ... immediate publication" of the test results, Harris testified.

Liggett attorney Donald J. Cohn said: "We're looking forward to the cross-examination," which could begin today. The other defendants in the trial are Philip Morris Inc. and P. Lorillard Inc.

Harris has testified for two days about his review of hitherto confidential records found in the companies' files, and of nearly 1,000 articles in the scientific literature on smoking and health from the early 1920s onward.

The trigger for the Arthur Little tests was a pathbreaking report by Dr. Ernest Wynder in 1953: He had applied tar from cigarette smoke to the shaved backs of 81 mice, and 44 percent of them developed cancer.

In response, several tobacco companies ran a January 1954 advertisement in which, Harris said, they used the word "cancer" for the first time.

The companies said in the ad that they didn't believe their products were "injurious to health."

Harris called the statement scientifically unwarranted, saying that by the late 1930s there was "scientifically credible" evidence of a link between smoking and lung cancer, and that he would have urged tobacco companies to undertake sustained research at once.

In written replies to pretrial questions from the plaintiff's lawyer, Marc Z. Edell, the defendant companies said they sponsored no research into the possibility of a link between smoking and cancer until after Wynder's report. By 1957, according to Harris, smoking had been "convicted of causing lung cancer." The industry continues to deny a link has been proven.

At Liggett, the reaction to Wynder's report was to retain Little in June 1954 to try to repeat the test Wynder had done with smoke from an unidentified "Brand X."

A Little official, R.L. Swaine, wrote in a 1954 memo: "If Chesterfield turns out to be negative and 'X' is positive, it would then be possible to say that by using Dr. Wynder's techniques Chesterfield did not produce cancer in mice."

The Little scientist who supervised the tests and wrote the 1962 article was Charles J. Kensler.

In another memo, Liggett research director Frederick R. Darkis said the company's "main concern was to produce cigarettes that the public will use, and then to make these cigarettes the best possible from a health standpoint."

In November 1955, Little reported that the duplicated Wynder tests showed that tars from the smoke of Chesterfields, L&Ms, and two unidentified brands caused cancer.

In Liggett's report to stockholders for 1957, President B.F. Few made no mention of this. Instead, he quoted congressional testimony for the tobacco industry by Dr. Harry S.N. Greene, chairman of pathology at Yale: "My feeling ... is that there isn't anything in tobacco that is carcinogenic, that is going to do the individual any harm."