GAINESVILLE, Fla. (AP) _ The United States has not received any credible threats to its nuclear power plants and there are multiple layers of defense in place to prevent an attack, a nuclear regulatory official said Saturday.

``I'm here to try to reassure the people of the United States that we are doing well,'' said Nils Diaz, one of five commissioners of the Nuclear Regulatory Commission, told an audience at the University of Florida.

Diaz, who has been in the industry for 40 years, also said he doesn't believe suspected terrorist mastermind Osama bin Laden or his al-Qaida terrorist organization has access to nuclear weapons.

``I believe they have no capabilities whatsoever,'' Diaz said. ``Some of those things are purposely planted to create fear.''

Since Sept. 11, the commission has tightened security as well as information it gives the public. Diaz would not elaborate on security measures, except to say that all nuclear power plants are on high alert.

``The bottom line is that the public health and safety will be protected even if there is an attack,'' Diaz said. ``There are multiple layers of defense.''