The disclosure of hidden tobacco money behind a study suggesting that lung scans might help save smokers from cancer has shocked the research community and raised fresh concern about industry influence in science.

Two medical journals that published studies by Weill Cornell Medical College researchers in 2006 are looking into tobacco cash and other financial ties that were not revealed. The studies reported benefits from lung scans, which the Cornell team has long touted.

It is a crucial public-health issue: Dozens of groups, including such antismoking crusaders as the American Cancer Society, have given the Cornell team funds to investigate whether routinely screening smokers with CT scans could spot the world's most lethal cancer in time to prevent deaths.

The federal government also has provided money, even though scientists have criticized the study's design and the government's own more rigorous study is under way.

Smokers are in dire need of good science on the risk and benefits of lung scans, which are being marketed directly to the public in shopping centers and similar settings. About a million people worldwide will be diagnosed with lung cancer this year, and most will die because it is found too late for treatment.

Advanced X-rays called spiral CT scans have been touted as a way to find tumors earlier. But doctors fear that screening could lead to too many false alarms and unnecessary biopsies without saving lives. The cancer society does not recommend them, and most insurers do not pay for them.

Interest in the scans soared after the Cornell researchers published a key study in 1999 saying they had found more tumors than conventional X-rays. Their ongoing study aims to prove the value of the scans, but it has been criticized because it lacks a comparison group.

Many scientists were stunned to learn that a foundation Cornell set up and listed in the New England Journal of Medicine in October 2006 as a sponsor of the study actually got $3.6 million from a parent company of the cigarette-maker Liggett Group Inc. The tobacco source was reported in yesterday's New York Times.

Liggett, whose owner was the first to break with other tobacco companies and say that tobacco was addictive and deadly, announced its donation to the Cornell foundation in 2000 in a news release. But the foundation's funding source was not disclosed to the journal.

Yesterday, company spokeswoman Carrie Bloom said in a statement that the company "had no control or influence over the research."

Scientists must maintain the trust of patients in research studies, and "any breach of that trust is not simply disappointing but, I believe, unacceptable," John Niederhuber, director of the National Cancer Institute, said in a statement.

Any findings from a study tainted by hidden industry ties "will be much less believable," said Sidney Wolfe, director of Public Citizen's Health Research Group.

The cancer society's chief medical officer, Otis Brawley, said the group would not have contributed to the study if it knew that "Big Tobacco" was helping to finance the work.

Still, there is no sign that the study's findings are tainted, and "it is my belief that something can be learned that can be useful," he said.

The chief Cornell researcher, Claudia Henschke, did not respond to an e-mail requesting comment.

Cornell's dean, Antonio Gotto, said: "The claim that we set this foundation up in order to cover up the money just isn't true. We made a public announcement that we were taking the money from the tobacco company."

In retrospect, Gotto said perhaps the tobacco cash and patents that Cornell researchers hold on related technology should have been disclosed in Henschke's journal articles. Instead, one listed only the Cornell foundation.

Catherine DeAngelis, editor in chief of the Journal of the American Medical Association, said she had contacted Henschke months ago after others pointed out patents not disclosed in a July 2006 study. DeAngelis said Henschke did not believe the patents were relevant to the research and resisted disclosing them.

"We'd been working with Dr. Henschke trying to get her to write a letter of apology - which is our policy - and to take responsibility," DeAngelis said. "It was not easy to get her to do anything."

Asked whether she would have published the research if the tobacco funding had been known, DeAngelis said: "Absolutely not. I would have turned down the paper."

A spokeswoman for the New England Journal, which published the Henschke paper listing the Cornell foundation as one of about 30 sponsors, said the publication was investigating the matter.