This photo provided by NASA shows Deputy NASA Administrator Shana Dale, center, speaking as Ellen Ochoa, director of flight crew operations, NASA Johnson Space Center, Houston, left, and Dr. Richard S. Williams, chief health and medical officer, NASA Headquarters, right, listen in at NASA headquarters in Washington, Friday, July 27, 2007, regarding a report that NASA let astronauts fly drunk on at least two occasions. [AP]

CAPE CANAVERAL, Fla. - After drinking heavily, an astronaut flew on a Russian spacecraft and another was cleared for flight on a space shuttle, said the chairman of an independent panel of outside experts Friday, citing unverified interviews.

The panel's report on astronaut health, released Friday, said NASA officials failed to listen to flight surgeons and other astronauts who warned of safety risks because some astronauts had too much to drink.

The news rocked the space agency anew and renewed concerns about whether NASA has fixed many of the problems that led to the demise of the space shuttle Columbia.

While the report was vague and gave no names, panel chairman Col. Richard Bachmann Jr., provided a few details. He said the panel was told about multiple instances involving alcohol, but the most detailed involved two astronauts.

In the case of the shuttle astronaut, a colleague warned he had had too much to drink but only after the mission was delayed for mechanical reasons, Bachmann said the panel was told. The astronaut had been going to fly a jet from Florida back home to Houston. Bachmann said he didn't know the outcome of that incident.

The second incident, he said, involved warnings of alcohol involving an astronaut flying on the Russians' Soyuz spacecraft headed for the international space station.

In such a situation, Russia would have the authority to overrule NASA if the U.S. space agency wanted to prevent the astronaut from flying. Whether NASA officials tried to intervene is unknown.

Ellen Ochoa, an astronaut who heads flight crew operations for NASA, said drinking and toasts are common in Russia, even just seven hours before flight.

Speaking by telephone to a news conference in Washington, Bachmann said it was not the panel's mission to investigate allegations or verify them and that NASA would have to ferret out details.

"There's certainly no intent to impugn the entire astronaut corps," Bachmann said. "We don't have enough data to call it alcohol abuse. We have no way of knowing if these are the only two incidents that have ever occurred in the history of the astronaut corps or if they're the tip of a very large iceberg."

The independent panel was created by NASA to assess its health screening after the high-profile arrest of astronaut Lisa Nowak in February after she drove across the country to confront a romantic rival.

The drinking allegations were a new humiliation for the space agency. Headline writers in newspapers and on the Web had as much fun as they did with the arrest of Nowak.

"Sauced in Space." "NASA: Shaken and Stirred." "Three-Martini Launch." "Houston, we have a drinking problem." The New York Post incorporated two giant bottles of Grey Goose vodka into a photo of the space shuttle.

At Friday's briefing, NASA said it was unaware of any astronauts being drunk before a flight. Deputy Administrator Shana Dale promised to pursue the truth behind the claims.

Four years age, another panel of experts urged NASA to repair a flawed safety culture that squelched warnings from lower-level employees. That board was created in the wake of the Columbia accident that killed seven astronauts.

Bachmann, an aerospace medical specialist with the Air Force, said his panel deliberately did not seek pertinent details about alcohol use, such as exactly when the drinking occurred. The overriding concern, he said, was that flight surgeons were ignored.

NASA has long had a policy that prohibits any drinking in the 12 hours before an astronaut flies a training jet. The space agency said that policy has historically been applied to spaceflights, too. But as a result of the panel's report, the rule will officially be applied to spaceflights, NASA said. An astronaut code of conduct also is in the works.

The commander of the next space shuttle mission, set for launch Aug. 7, has already met with NASA's chief safety official to discuss behavior expectations for the upcoming flight. Both commander Scott Kelly and the crew's lead flight surgeon were encouraged to raise any safety issues, Dale said.

Only four paragraphs of the 12-page report dealt with alcohol use by astronauts.

"Two specific instances were described where astronauts had been so intoxicated prior to flight that flight surgeons and-or fellow astronauts raised concerns to local on-scene leadership regarding flight safety," the panel. "However, the individuals were still permitted to fly."

The panel said alcohol is freely used in the crew quarters, where astronauts are quarantined at the Kennedy Space Center in the three days before launch.

The eight-member panel included experts in aerospace medicine and medical legal matters, and clinical psychiatrists, all affiliated with government agencies.

The panel said that NASA is not set up to deal with alcohol use by astronauts.

"The medical certification of astronauts for flight duty is not structured to detect such episodes, nor is any medical surveillance program by itself likely to detect them or change the pattern of alcohol use," the panel wrote.

The panel recommended that NASA hold individuals and supervisors accountable for responsible use of alcohol, and that policies be instituted involving drinking before flight.

Bachmann and his group acknowledged that some of the cultural issues cited in the report have existed since the beginning of the astronaut program. The early spacemen were fighter pilots who often lived and drank hard; that was the essence of being a test pilot, recalled Seymour Himmel, a retired NASA executive.

"I remember some of our pilots used to say they didn't drink within 12 feet of a ship or smoke the day before," he said with a laugh. "These were very good test pilots."

In another finding, the panel reported that flight surgeons' medical opinions were not valued by higher-ups. Several senior flight surgeons told the panel that officials only wanted to hear that all medical systems "were `go' for on-time mission completion" and ignored their medical advice.

"This disregard was described as 'demoralizing' to the point where they said they are less likely to report concerns of performance decrement," the panel wrote.

The panel recommended that astronauts have psychiatric evaluations as part of their yearly physical exams, something that is not the case now.

Fourteen astronauts, all but one with spaceflight experience, were interviewed by the panel, as well as five family members. In addition, eight flight surgeons were interviewed.