Cuban officials have made a lengthy presentation on a series of mysterious illnesses suffered by U.S. and Canadian diplomats in Havana, reiterating that no evidence supports allegations that the symptoms resulted from high-tech attacks.

The officials said Thursday that they don't dispute that diplomats became ill, but suggested that many of the cases consisted of ordinary illnesses that were erroneously blamed on a mysterious single phenomenon due to the high degree of attention focused on the case.

Mitchell Valdes-Sosa, director of Cuba's Center for Neuroscience, said that a review of U.S. studies of the illnesses showed that some had begun before the start of the supposed phenomenon, and others consisted of a wide range of symptoms that hardly ever result from the same disease.