A few more news outlets are picking up on the Mars methane stories.

The second group to detect signals of methane in the Martian atmosphere is led by Michael Mumma of Nasa's Goddard Space Flight Centre in Maryland, who used powerful spectroscopic telescopes based on Earth.

This team is even believed to have detected variations in the concentrations of methane, with a peak coming from the ancient Martian seabed of Meridiani Planum, which is being explored by a Nasa rover.

This could indicate a subterranean source of methane which is pumping out the gas, either due to some residual geological activity or because of the presence of living organisms producing it as a waste gas.

Asked whether the continual production of methane is strong evidence of a biological origin of the gas, Dr Mumma said: "I think it is, myself personally."

He added: "It's difficult to imagine that primordial methane [from geological activity] would continue outgassing for four billion years [the age of Mars]. This looks very intriguing."

Both teams of scientists are now busy validating their results before their respective organisations are prepared to go public on the implications.