NEWARK, FEB. 29 -- A former top officer of Philip Morris Inc. today disputed company scientists on the effects of nicotine on smokers who have trouble giving up cigarettes.

The dispute bears on a core issue in cigarette product-liability litigation: Do smokers become dependent upon cigarettes, or do they continue the habit out of free choice?

The scientists' views emerged from confidential Philip Morris documents obtained by the plaintiff for a smoker-death lawsuit.

Joseph F. Cullman III, former chairman and chief executive, was asked about the papers in his fourth day on the stand in U.S. District Court here.

One of the documents was a company scientist's statement that nicotine has "powerful" effects on the body and "may be the most important component of cigarette smoke."

"Nicotine and an understanding of its properties are important to the continued well being of our cigarette business since {it} has been cited often as 'the reason for smoking'," J.L. Charles said in a memo to his supervisor.

Nicotine had effects on the "nervous system as well as influencing memory, learning, pain perception, response to stress and level of arousal," Charles added.

He wrote the memo in 1980, while Cullman was chairman of the executive committee. Cullman testified he hadn't known of the memo, "nor do I agree with it."

Cullman acknowledged to Alan M. Darnell, a lawyer for widowed plaintiff Antonio Cipollone, that nicotine is a drug, and said that for most smokers, "I certainly think it is difficult to quit smoking."

In 1971, seven years before Cullman retired as chairman and CEO, William L. Dunn Jr., the company's principal associate scientist, told an industry-sponsored conference why people smoke: "The cigarette should be conceived not as a product but as a package. The product is nicotine."

Darnell today asked Cullman whether Philip Morris was selling cigarettes or nicotine. "I would say without any question we were selling cigarettes," Cullman said.

In his 1971 speech, Dunn also said "the physiological effect {of smoking} serves as the primary incentive; all other incentives are secondary.

"The majority of the conferees would go even further and accept the proposition that nicotine is the active constituent of cigarette smoke. Without nicotine, the argument goes, there would be no smoking," Dunn said.

Cullman today told the jury that he hadn't heard Dunn's talk, and testified that "I would say we had a different viewpoint."

Philip Morris research chief Helmut Wakeham told Cullman and other board members in 1969 that "nicotine in smoke is directly proportional to the ... tar," and that "the ultimate explanation for the perpetuated cigarette habit resides in the pharmacological effect of smoke upon the body of the smoker."

"Was it necessary to have a certain amount of nicotine in your cigarettes?" Darnell asked.

"No," Cullman said. "We were delighted to bring tar and nicotine levels down."