According to Mexican physicians, the two reported "non-human" alien corpses each belonged to a single skeleton and were not assembled.

After academics, scientists, and archaeologists said the remains were a fraud, the doctors conducted a number of scientific tests on them.

Professor Brian Cox, a physicist and television host, was one of several who criticized them, saying they were "way too humanoid" to be real.

In a hearing that sparked excitement among UFO enthusiasts, the mummified specimens were on display in glass cases as part of an official reveal last week in Mexico's Congress.

Politicians were informed that the remains were thought to be 1,000 years old and had been discovered in Cusco, Peru.

Jaime Maussan, a journalist and UFO researcher, organized the event in Mexico City. According to Mexican media, he testified under oath that the specimens' about one-third of their DNA is "unknown" and that they are not products of "our terrestrial evolution."

"These specimens are not part of our evolutionary history on Earth," he said in his presentation to Mexican government officials and representatives from the US.

"They are not beings recovered from a UFO crash. Instead, they were found in diatom (algae) mines and subsequently became fossilised."

Prof. Cox has advocated sending a sample to the biotechnology firm 23andme for impartial confirmation that the samples aren't extraterrestrial.

"It's very unlikely that an intelligent species that evolved on another planet would look like us," he said last week.

Mr. Maussan has made claims of having discovered extraterrestrial life before.

He asserted in 2015 that a mummified body discovered in Peru's Nazca region belonged to an alien, but it was ultimately determined to be the remains of a human infant.

The mummified remains that UFO enthusiasts allege are aliens are typically modified human bodies, according to academics, archaeologists, and scientists.

They claim that the remainder, especially the smaller ones like those displayed in Mexico last week, are bodies put together from the bones of both animals and people.

The examinations performed on Monday by Mexican medical professionals, however, imply that they were not built but rather were taken from a single skeleton.

Speaking to the delegation from Mexico City about his supposed discovery from last week, Mr. Maussan said that the specimens had previously undergone examination at the Autonomous National University of Mexico.

He claimed that one had "eggs" within, as revealed by X-rays, and that experts had used radiocarbon dating to acquire DNA proof.

Politicians in Mexico said last week that they will "continue talking about this" because the material had given them "thoughts" and "concerns."