New Mars discoveries are advancing the case for possible life on the red planet, past or even present.

Scientists reported on Thursday that Nasa’s Curiosity rover has found potential building blocks of life in an ancient Martian lakebed. Hints have been found before, but this is the best evidence yet.

The organic molecules preserved in 3.5 billion-year-old bedrock in Gale Crater - believed to once contain a shallow lake - suggest conditions back then may have been conducive to life. That leaves open the possibility that microorganisms once populated our planetary neighbour and might still exist there.

"The chances of being able to find signs of ancient life with future missions, if life ever was present, just went up," said Curiosity’s project scientist, Ashwin Vasavada of Nasa’s Jet Propulsion Laboratory in Pasadena, California.

Curiosity also has confirmed sharp seasonal increases of methane in the Martian atmosphere. Researchers said they can’t rule out a biological source. Most of Earth’s atmospheric methane comes from animal and plant life, and the environment itself.