Bush administration officials, however, said they were standing by their assertions that Cuba has at least a limited biological warfare program and has shared such biotechnology with rogue states. One allegation says those states are Iran and Libya, Carter said.
Carter, the first U.S. head of state in or out of office to visit Cuba since Fidel Castro's 1959 revolution, also met at his hotel with two leading Cuban dissidents for a briefing on human rights. The opposition leaders called on Carter to promote dialogue between the two countries.
During a Monday morning tour of the Center of Genetic Engineering and Biotechnology, Carter told Castro and this country's top scientists that he had asked White House, State Department and intelligence officials specifically if Cuba was transferring technology or other information that could be used in terrorist activities.
"The purpose of this briefing was for them to share with us any concern that my government had about possible terrorist activities that were supported by Cuba," said Carter. "There were absolutely no allegations made or questions raised. I asked them specifically on more than one occasion if there was any evidence that Cuba has been involved in sharing any information to any other country on Earth that could be used for terrorist purposes. The answer from our experts on intelligence was 'no'," Carter told the gathering at Cuba's top biotechnology lab.
CBS News Correspondent Jim Axelrod reports that Carter's response to the U.S. allegations was startling in its contrast to administration claims that Cuba is exporting the weapons technology.
Speaking a few feet from Castro, Carter shared details of his pre-trip briefings with U.S. officials.
"These allegations were made, maybe not coincidentally, just before our visit to Cuba," Carter said of concerns Undersecretary of State John Bolton raised last week during a meeting of the Heritage Foundation, a conservative research group in Washington.
The former president said Cuban scientists deny they have any technology transfer program with Libya and that a new program with Iran is not functioning yet. Dr. Luis Herrera, director of the Center of Genetic Engineering and Biotechnology, said his country had no program with Iraq, either.
A State Department official said Monday that Carter was not briefed on the weapons issue because his briefing occurred before the allegations by Bolton last week in Washington.
In his remarks at the time, Bolton said he believes Cuba has at least a limited offensive biological warfare research and development effort.
"Cuba has provided dual-use biotechnology to other rogue states," Bolton said. "We are concerned that such technology could support BW programs in those states. ... We call on Cuba to cease all BW-applicable cooperation with rogue states and to fully comply with all of its obligations under the Biological Weapons Convention."
Havana has denounced Bolton's allegation as a lie and promised Carter "complete access" to any Cuban biotechnology laboratory.
As Castro sat next to the former American president in an auditorium at the lab, Cuban scientists told Carter that their transfer contracts with other countries forbid the use of Cuban technology for anything other than the vaccines and other lifesaving technology purposes they were designed for.
Answering a question from Carter, Herrera insisted that Cuba monitors the use of technology transferred to other countries to ensure it is not used for terrorism.
"I just want to assure myself," Carter said.
Traveling with his wife and a small group of executives and staff from his Carter Center, the former American president had no biotechnology experts in his delegation for the visit. Carter has a science background, but in nuclear technology.
Elizardo Sanchez and Oswaldo Paya, the dissidents who met with Carter, are both coordinators of Project Varela, a proposed referendum asking voters if they want guarantees of individual freedoms, an amnesty for political prisoners, the right to own their business and electoral reforms.
Paya said the men explained the need for dialogue. "Carter understands the concept very well because he is a man of dialogue."
In Washington, a White House spokesman said Monday that Castro should give his own people the same freedom to travel and speak to dissidents that he has given Carter.
"Why have one standard for a visitor and have a far worse, much more repressive standard for his own people?" Ari Fleischer said.
Carter, who did more than any other president to ease tensions with Cuba, arrived Sunday to the strains of "The Star-Spangled Banner." Castro turned to his visitor and said, "It's been a long time since that happened."
Sunday night, a dark-suited Castro threw a dinner for Carter and his delegation at the Palace of the Revolution. The visit gave the Cuban leader a chance to reach out to Americans, and he used it by symbolically throwing open the doors of the island to Carter.
Castro said a Carter speech on Tuesday would be broadcast live. "You can express yourself freely whether or not we agree with part of what you say or with everything you say," Castro said. "You will have free access to every place you want to go."
"We shall not take offense at any contact you may wish to make," he added, an obvious reference to the dissidents and human rights activists Carter planned to meet.
Cuban officials have been irritated with some other foreign leaders who have held similar meetings, but Castro said Carter had proved his sincerity in the past.
"A man who, in the middle of the Cold War and from the depth of an ocean of prejudice, misinformation and distrust ... dared to try to improve relations between both countries deserves respect."
Speaking in Spanish, Carter said he hoped "to discuss ideals that Rosalynn and I hold dear ... peace, human rights, democracy and the alleviation of suffering."