WASHINGTON. Aug . 7: Researchers testing a meteorite from Mars claim to have found evidence that primitive life once lived on the red planet. Other scientists scoffed Tuesday and said stronger evidence is needed, reports AP.

Scientists from NASA and three American universities say chemical and microscopic tests of a rock from Mars detected organic compounds deposited in such a way that they could have come only from biological activity.

They also report seeing shapes that "resemble some forms of fossilised filamentous bacteria.’’ although much smaller.

When studying these factors. the researchers report.

"we conclude that they are evidence for primitive life on early Mars."

The study is to be published next week in the journal Science. The journal released draft eqpies Tuesday after the contents Were leaked.

Carl Sagan, a leading authority on the search for extraterrestrial life, called the findings "evocatA-e and very existing." But he said the chemical compounds reported in the paper "are not evidence of life."

Other scientists were more skeptical, saying the organic compounds found by the researchers could have been formed without life.

Past or present existence of

life on Marsh has been consid ered a possibility ever since studies oy spacecraft landers showed that water was once present on the planet surface.

None of the Martine landers. however, found evidence that life now exists on Mars, nor did the robot craft find chemical markers for life in limited soil samples that have been analyzed.

The researchers say in the paper that a rock from space recovered in Antarctica contains organic compounds that could only have been deposited by biological activity. .

The new findings center on a meteorite callea Allan Hills 84001, the oldest of 12 pieces of tock that Earlier studies

confirmed as originating from Mars.

Studies show that Allan Hills 84001 was crystallised from melted rock about 4.5 billion years ago. a time when the solar system was forming.

The rock is thought to have been knocked from the Martin surface about 15 million years ago and then landed on the Antarctic ice sheet about 13.000 years ago. It was discovered in 1984 and identified as originating from Mars.

Scientists from NASA's Johnson Space Center, from Standford University, the University of Georgia and from McGail University in Montreal, recently studied thin slices of the rock that revealed organic molecules called polycyclic

aromatic hydrocarbons, or PAHs.

They said PAHs can be formed only in two ways - by biological action, such as by microorganisms, or In the process that forms planets

The researchers deter mined that the PAHs in the rock Were deposited In cracks that occurred after the mete orite was formed, suggesting the molecules were deposited by later biological activity.

Also, the researchers said that within the PAHs. they found particles of magnetite and iron sulfide, both chemicals that can be related to bacterial action.

Sagan said that If the researchers did. in fact, find mi-

crofossils within the Mars rock then that would represent the strongest evidence yet of life beyond the Earth.

But if the researchers' claim is based on the presence of or-ganic chemicals, he said. "life, while possible. Is not proven on Mars."

Referring to the organic compounds. Jack D. Farmer said. If that's the evidence. 1 don't believe it

Farmer, a geologist and palebiologlst of the Exobiology Branch oft NASA s Ames Research Centre in Mountain View. California, said the bulk of magnetite is inorganically formed and that "PAHs have no direct relationship to biology. They are not an indicator." J