The fossilised bodies presented in glass cases by journalist and UFO scientist Jaime Maussan at Mexico's parliament are said to be 1,000 years old.
The bodies of two alleged "alien" beings were exhibited before politicians in a special session of the Mexican Congress on Wednesday.
The fossilised bodies, presented by journalist and self-proclaimed UFO scientist - or ufologist - Jaime Maussan and displayed in glass cases, were retrieved from Cusco in Peru and are said to be 1,000 years old.
"These specimens are not part of the evolution of our world. They were not recovered from a UFO scrap. They were found fossilised in a diatom moss mine," Maussan said, testifying under oath.
Maussen said the samples were analysed by the National Autonomous University of Mexico (UNAM) and the scientists who managed to get DNA samples from the specimens and used radiocarbon testing to determine their age.
However, despite the intensive examination, the fossils were found to be covered with a layer of sand.
"We are not alone in the vast universe, we need to accept this reality," said Maussan, who argued that the public has the right to learn about non-human beings and technologies.
Maussen was accompanied at the session by former US pilot Ryan Graves and Avi Loeb, professor of astrophysics at Harvard University. Graves also presented evidence at a hearing in the US Congress in July.
It is now generally accepted in scientific and political circles that there are unusual phenomena that cannot be identified, but there are still deep disagreements about their origin.
Maussen gave testimony under oath but his claims have not been scientifically proven and has been associated with previous discoveries that have since been debunked.
He was involved in another high profile hoax in 2017 involving the discovery of fossilised remains in Nazca in Peru.
Maussan claimed the body, which had an elongated skull, was actually the mummifed corpse of an alien.
It was later revealed that the Nazca mummy was in fact a human child whose head had been bound by cloth, rope or boards in an ancient practice