Space invaders aren't the only ones kidnapping unsuspecting Americans and forcing them to undergo medical examinations, according to one of three alleged alien abduction victims who spoke here Thursday.

Melinda Leslie, an Orange County, Calif., woman who leads a support group for self-described abductees, said more than three dozen people who believe they have been taken aboard alien spacecraft - including herself - have been re-abducted by apparent military personnel and subjected to physical examinations and interrogation.Leslie, addressing an audience of about 300 here at the fifth annual International UFO Congress, said humans in a "flying triangle" abducted her and took her to an underground testing facility. There, men in hazardous-material jumpsuits performed an extensive gynecological exam and other medical procedures on her, she said. She was abducted by humans a second time and interrogated by a red-haired "military captain" who demanded that she tell him everything she knew about the aliens.

Men in uniform also have been present during some alien abduction experiences, including one of the half-dozen Leslie has had, she said. She and other abductees have been targets of continued surveillance and harassment by these same people, she added.

"It's the government or a shadow part of the government or a paramilitary organization or even a civilian military program," Leslie said. "I think this says a lot about the UFO cover-up. We are flying discs we built using alien technology with both the military and aliens aboard them."

Leslie said in researching her experiences she has talked to several people who claim to have been involved with covert government operations. Based on those conversations, she believes humans in some official capacity may be interacting with extraterrestrials in some type of cooperative partnership.

Leslie said these humans either do not trust the aliens and are spying on them, or are curious as to the limits of alien technology - perhaps because the aliens have made threats and the people are searching for a weakness in their apparent control of the situation.

"The cover-up is disorganized and foolish," Leslie said. "It is desperate men taking desperate measures. They don't have control of the situation like they'd like to. There are a number of insiders who want the information out and are beginning to leak it."

Leslie said she is working with Kathy Kasten, who also claims to be an abductee and was not in attendance Thursday, to persuade the federal Health and Human Services Department to investigate the covert research group they believe is behind the alleged re-abductions. The activity warrants an investigation, she said, because federal regulations require human subjects involved in research to sign an informed consent form - something the human abductors are not asking these civilians to do, she said.

Leslie said Kasten received an Aug. 29 letter from Lana R. Skirboll, director of the National Institute of Mental Health's Office of Science Policy and Program Planning. In it, she said, Skirboll said the agency needed more information from the alleged re-abduction victims - including name, address and Social Security number - before it can make any determination. Leslie circulated a letter asking members of the audience who believe they were abducted by both aliens and humans to answer a series of questions for submission to Skirboll.

A spokesperson for the Office of Science Policy and Program Planning in Washington, D.C., said Friday that Skirboll is no longer the director of that office. Another employee confirmed that office only deals with research projects involving people who have mental health disorders. The Health and Human Services Department's Office for Protection from Research Risks oversees other types of human research, she said.

A spokesperson for NIMH confirmed the letter was sent to Kasten but said the point of it was only "to say we don't think it has anything to do with the NIH or NIMH research, but if you give us some more information we'll look it up and see."