HAVANA, May 13 - Former President Jimmy Carter said today that Bush administration officials who briefed him before his trip to Cuba never mentioned any concerns about Cuban involvement in developing biological weapons.

His comments came as Secretary of State Colin L. Powell cast some doubt on assertions last week by a senior State Department official that Cuba was making such weapons.

Mr. Carter described the briefings, with White House and intelligence officials, as ``intense.'' They finished just days before the senior official, John R. Bolton, charged that Cuba had developed ``at least a limited offensive biological warfare research and development effort'' and also ``provided dual-use biotechnology to other rogue states.''

Mr. Carter, speaking at a Cuban biological research center before an audience that included President Fidel Castro, said: ``There were absolutely no such allegations made or questions raised. I asked them myself on more than one occasion if there was any evidence that Cuba has been involved in sharing any information with any country on earth that could be used for terrorist purposes. And the answer from our experts on intelligence was no.''

He hinted that the State Department announcement was an attempt to undercut his visit. He is the most prominent American political figure to visit Cuba since Mr. Castro came to power in a 1959 revolution. ``With some degree of reluctance, I would like to comment on the allegations of bioterrorism,'' Mr. Carter said. ``I do this because the allegations were made, perhaps not coincidentally, just before our visit to Cuba.''

He spoke at the start of a tour of the Center for Genetic Engineering and Biotechnology in Havana, after a long presentation on Cuba's biomedical and genetic research. Cuban officials made no direct comments today about Mr. Bolton's charges.

Mr. Carter said he did not believe that Cuba was collaborating with Libya in biological research, adding that its scientific relations with Iran conform to international standards.

Secretary Powell, speaking to reporters while traveling to a NATO meeting in Iceland, said that while the administration believes that Cuba has the ability to produce biological weapons, it stops short of claiming that it has actually done so.

``As Undersecretary Bolton said recently, we do believe Cuba has a biological offensive research capability,'' Mr. Powell said. ``We didn't say it actually had some weapons, but it has the capacity and capability to conduct such research.''

But Condoleezza Rice, the national security advisor, said during an interview on the PBS program ``The News Hour with Jim Lehrer,'': ``You can't show someone a biotech lab and be assured they're not creating weapons of mass destruction. That's not how biotech wweaons work. And they're actually very easy to conceal and you need multiple measures to make certain biotech weapons aren't being developed and transferred.''

The center Mr. Carter visited has attracted thousands of foreign scientists, including 400 Americans last year. Doctors involved in the research said the American allegations misconstrued their efforts to make vaccines and other products that have helped many third world residents. ``Those accusations offend us as scientists,'' said Dr. Ricardo Bringas, a biologist who analyzes genetic patterns. ``The last thing we are thinking of is to hurt someone.''