By STEVEN R. WEISMAN
 
ASHINGTON, Sept. 17 - The Bush administration, using stringent standards adopted after the failure to find banned weapons in Iraq, has conducted a new assessment of Cuba's biological weapons capacity and concluded that it is no longer clear that Cuba has an active, offensive bio-weapons program, according to administration officials.

The latest assessment contradicts a 1999 National Intelligence Estimate and past statements by top administration officials, some of whom have warned that Cuba may be sharing its weapons capacity with "rogue states" or with terrorists.

It is the latest indication that in the wake of the Iraq intelligence failures, the C.I.A. and other intelligence agencies are taking a closer look at earlier threat assessments and finding fault with some of the conclusions and the way the reports were prepared.

The new assessment says the intelligence community "continues to believe that Cuba has the technical capability to pursue some aspects of an offensive biological weapons program," according to an intelligence official.

He added, "There is still much about Cuba that is cause for concern, including the production and export of dual-use items and cooperating with countries on the State Department's list of state sponsors of terrorism." The term "dual use" refers to items that could be used for both civilian and military programs.

Administration officials said that the new assessment had been prepared at the request of the State Department for a report it will be making to Congress and that it had adopted tougher standards because the past assessment on Iraq had been proved wrong.

"The new assessment is the product of a fresh, hard look at the reporting," said an intelligence official. He added that the new standards were "exceptionally stringent in how we treat our sources, evidence and analysis."

The Bush administration's past assessment accusing Cuba of producing germs for possible biological warfare has been a matter of dispute since it was first disclosed in the spring of 2002. Cuba angrily disputed the charges, and some experts suggested that Cuba's large pharmaceutical industry involved conventional activities and materials that were misinterpreted as a threat by opponents of Fidel Castro, the Cuban leader.

In March 2002, John R. Bolton, under secretary of state for nonproliferation, asserted that "the United States believes that Cuba has at least a limited offensive biological warfare research and development effort'' and had also "provided dual-use biotechnology to other rogue states.''

A month later, he ratcheted up his comments that Cuba remained a "terrorist" threat to the United States and that its biological weapons program should be seen in that light. Mr. Bolton declined to comment on the revised assessment on Friday.

Around the same time, Carl Ford, the assistant secretary of state for intelligence and research, reported the same formulation to the Senate Foreign Relations Committee on Cuba. He listed Cuba as a country over which the United States was "most concerned" in the category of possessing chemical and biological weapons.

Mr. Bolton's warnings were applauded by supporters of a tough line on Cuba, many of whom are supporters of President Bush's re-election and are based in Florida. But there were dissenters even within the administration who said privately that Mr. Bolton seemed to be exaggerating the nature of the threat.

The new intelligence assessment was described by an intelligence official and a second government official. Both said they had been briefed on it. They spoke on condition that their names and agencies not be identified.

Both officials said they believed that the new assessment was more accurate than the old one and reflected a welcome effort by American intelligence agencies in the wake of the Iraq experience to acknowledge uncertainties in their analysis.

A new National Intelligence Estimate on biological weapons is being prepared and is still several months from completion, administration officials said.

A State Department official, asked to comment on the new assessment, said, "We don't comment on reported intelligence matters."

The intelligence official who was familiar with the new assessment said the intelligence community continued to believe that Cuba "has the technical capability to pursue some aspects of an offensive biological weapons program" but that "as a result of the reassessment, it is unclear whether Cuba has an active, offensive biological weapons effort under way."

The officials also said that even the original report was accompanied by cautionary information suggesting that the conclusion had been based on partial information.

"The intelligence community knew and informed its customers at the time that the sourcing behind that conclusion was fragmentary, and that there were some problems with some of the reporting used in that argument," said an official, referring to the earlier assessment of the danger posed by Cuba.

The original National Intelligence Estimate in 1999 said Cuba had "at least a limited, developmental biological weapons research and development effort," according to the intelligence official.

Mr. Bolton employed that same language in addressing the issue, as has Roger F. Noriega, assistant secretary of state for Western Hemisphere affairs.

The intelligence official said it was not unusual for experts to review their findings on weapons of mass destruction.

"The intelligence community constantly reassesses its evidence, tradecraft and the judgments that flow from them," he said. "And in light of the lessons learned from the Iraq W.M.D. estimate, we are being exceptionally stringent in how we treat our sources, evidence and analysis. Others expect that of us, and we expect that from ourselves."

At the time of Mr. Bolton's assessment in 2002, his office declined to elaborate on what sort of weapons might have been the focus of Cuba's program. Other administration officials were quoted in The New York Times as saying that Cuba had been experimenting with anthrax and other deadly pathogens that they declined to identify.

Cuba, however, has a major drug and biotechnology program and has been involved in making vaccines for an extensive immunization program that has been widely praised by scientists and physicians. Many of these products are sold to other countries.

Some of these sales have been cited by some experts as evidence of a potential threat from Cuba, although the latest assessment is likely to be seen as supplying a cautionary note.