A former asbestos-products manufacturer has gone to court to try to force cigarette companies to share liability in suits by asbestos workers who smoked and who claim to have contracted serious or fatal lung diseases from exposure to the mineral.

GAF Corp., a large manufacturer of building materials and chemicals, is basing the effort on long-known medical evidence that smoking sharply increases the risks of asbestos-related lung cancer and other diseases in asbestos workers.

Although it is a defendant in an estimated 20,000 to 30,000 asbestos product-liability cases, GAF is a relatively small player in the massive litigation in which the principal target has been Manville Corp., which is in a controversial voluntary reorganization under Chapter 11 of the federal bankruptcy law.

GAF, a Wayne, N.J., company, sold asbestos products for several years after 1967, when it merged with Ruberoid Corp., but then phased them out.

The defendants named by GAF in papers filed in Superior Court in Oakland, are five of the six leading tobacco companies: American Brands, Philip Morris, R. J. Reynolds, Brown & Williamson, and Liggett Group.

If cigarettes can be shown to be a "significant element" in diseases blamed entirely on asbestos, "that element of the cost should properly be borne by the tobacco companies," William H. Armstrong, of GAF's San Francisco law firm, said in an interview.

Over the last three weeks, Armstrong said, his firm, McCutchen, Doyle, Brown, & Enersen, has filed a "cross-complaint" against the cigarette makers in each of 170 cases in which his client has been sued by an asbestos worker who smoked. He estimated the first case will not go to trial for at least nine months.

Armstrong also said the firm will file more such complaints, noting that about 2,300 suits are pending against GAF in the Bay Area alone. His "rough evaluation" was that "well over half" of the plaintiffs had disease associated with tobacco.

The unnamed defendants in the cross-complaints also include cigarette distributors and retailers, tobacco-company marketing, advertising executives and others.

The cross-complaints generally deny GAF's liability to plaintiffs, but say that if it is found liable, it is entitled to a determination by the courts "of the relative percentage of fault attributable" to GAF and the tobacco industry defendants.

An industry spokesman who asked not to be named said that the situation is "all very new" and that attorneys for the cigarette companies will meet shortly to devise defense strategies.

In Washington, Murray H. Bring of Arnold & Porter, Philip Morris' counsel, emphasized that the plaintiffs themselves had not sued the cigarette companies and that only one asbestos company has moved to involve the industry. "I suspect that they may have taken this action to complicate that asbestos litigation," Bring said.

In San Francisco, George W. Kilbourne, a lawyer for several of the asbestos workers who had smoked, said that the GAF action "is probably a feeler on the part of the asbestos industry to recoup some of its insurance losses. I doubt very seriously that GAF is really behind this -- I suspect that it's their insurance carrier."

Kilbourne also said that he thinks GAF "has an excellent chance of winning" over the tobacco firms.

In Boston, Northeastern University law professor Richard Daynard, co-chairman of the Tobacco Products Liability Project, said that "GAF's action multiplies by a factor of six the number of product-liability suits pending nationally against the tobacco industry."

Studies have indicated that the lung-cancer risk in a person who is a long-time asbestos worker and smoker is 50 to 90 times higher than in a person who is neither. But mesthelioma, a highly malignant cancer in the tissues surrounding the lungs, is attributed almost entirely to asbestos.

An effort similar to GAF's was made by a small asbestos company a few years ago in San Francisco, but it failed after the case was transferred to federal court from Superior Court and ran afoul of legal complications.