The evidence was said to be contained in the ALH84001 meteorite knocked off Mars billions of years ago and discovered in the Allen Hills of Antarctica in 1984.
But since then scientists have disputed the claims, some of which have been quietly withdrawn by the Nasa agency.
"The case has weakened dramatically," said Horton Newsom, a meteorite expert from the University of New Mexico, after a conference held in Houston earlier this month to discuss ALH84001. He added that "a number of the lines of evidence have gone away".
In particular, one of the planks of the original work, which suggested that sub-microscopic "worm-like" tubes were the leftovers of bacterial cells, is no longer considered tenable.
Now Professor Colin Pillinger, of Britain's Open University - who heard this week that his plan for a robot probe to Mars, code-named Beagle, will receive European funding - says: "Let's go there and do the experiment in the best possible way.
"Let's see if we can find organic matter in sub-surface rock samples."
He added that if the probe failed to find anything, "then maybe we'll have to think again... but I've always wanted more evidence than just the suggestion of fossils in a meteorite."Reuse content