Could there be life on Mars after all?

Washington: A surprising and mysterious belch of methane gas on Mars hints at possible microbial life underground, but also could come from changes in rocks, a new Nasa study found.

The presence of methane on Mars could be significant because by far most of the gas on Earth is a byproduct of life - from animal digestion and decaying plants and animals. It may possibly be the latest indication that life can be sustained on the Red Planet.

Past studies indicated no regular methane on Mars. But new research using three ground-based telescopes confirmed that nearly 21,000 tons of methane were released during a few months of the late summer of 2003, according to a study published on Thursday in the online edition of the journal Science.

The presence of methane implies active geological, or possibly even biological, processes on Mars.