MIAMI, SEPT. 30 -- The government case against Manuel Antonio Noriega developed a potentially damaging hole today when Floyd Carlton Caceres, the star prosecution witness, testified that Noriega never provided him protection for planeloads of cocaine that Carlton was flying into Panama.

Despite his testimony last week that he passed along $600,000 in bribes from the Medellin drug cartel to Noriega, the convicted pilot acknowledged under cross-examination today that he never told Noriega in advance about when and where his cocaine flights would occur and that Noriega did nothing to assist them.

"I didn't give General Noriega absolutely any type of information" about the flights, Carlton testified in response to rapid-fire questions from Frank Rubino, the former Panamanian leader's chief attorney.

When Rubino asked whether Noriega did anything to aid the flights, such as deploying Panamanian soldiers to secure landing strips or ordering customs officials to conduct sham inspections, Carlton responded: "Absolutely nothing."

The admission appeared to expose a weakness in what last week was being credited as devastating testimony by Carlton. Allegedly acting as intermediary between Noriega and Medellin drug bosses Pablo Escobar and the late Gustavo Gaviria, Carlton had offered a detailed account of how Noriega repeatedly escalated his demands for payoffs in exchange for approval for four drug flights between 1982 and 1983.

But today Carlton's testimony drew withering and sarcastic comments from Rubino, who repeatedly asked why Escobar and the cartel bothered to bribe Noriega if he was not helping to protect the flights. Rubino charged Carlton was simply trying to "shake down" the cartel by "trading" on Noriega's name.

Instead of paying an initial $100,000 bribe to Noriega for his first drug flight, Rubino asked, "Isn't it true that you just stole an extra $100,000 from the cartel, put it in your pocket and never gave anything to General Noriega?"

Carlton, once Noriega's personal pilot, stuck by his account and said he needed Noriega's approval for the flights because "we never did anything in Panama that he didn't allow." He also said he paid Noriega "so there would be somebody who would take care of me in case I got into trouble."

From the beginning, Carlton, 42, has been considered among the most critical witnesses in Noriega's drug-trafficking and racketeering trial because he is one of few people who can link him directly to drug payoffs. Law-enforcement officials had contended privately that Carlton's story -- first offered to a Senate subcommittee three years ago -- seemed unimpeachable.

But Rubino picked at apparent inconsistencies and other possible weaknesses in the account. Carlton acknowledged that no one witnessed any of his conversations with Noriega about drugs. "We weren't talking about cookies here," he said. "I couldn't tell him about these things in front of other people."

Last week, Luis Del Cid, another key government witness, had testified that he accepted two envelopes of "drug money" from Carlton that he then passed to Noriega. Del Cid said he never opened the envelopes but knew that they contained money because he "felt" the contents.

But today, under Rubino's prodding, Carlton testified that, in the case of the first payment of $100,000, he did not pass the money in an envelope but in a hard cardboard box wrapped in plastic.

Rubino also hammered away at what he called the "deal" offered by the government in exchange for testimony against Noriega. Arrested in Costa Rica in 1986 and extradited to the United States, Carlton was indicted the next year on nine cocaine charges carrying a total maximum penalty of life in prison plus 145 years with no parole.

But after Carlton began telling federal officials about his involvement with Noriega, prosecutors dropped all but one charge and Carlton was paroled. As part of his plea agreement, Carlton testified, he was allowed to keep a ranch and other properties in Panama. In addition, he is in the federal witness-protection program, and the federal government has spent $211,681 to support him, he acknowledged. This included free living quarters for him, his wife and two children plus a car and a babysitter's salary and living expenses, he added.