The researchers examined samples from six meteorites of volcanic rock that originated on Mars. The meteorites contain gases in the same proportion and with the same isotopic composition as the Martian atmosphere.
All six samples also contained methane, which was measured by crushing the rocks and running the emerging gas through a mass spectrometer.
The team also examined two non-Martian meteorites, which contained lesser amounts of methane.
The discovery hints at the possibility that methane could be used as a food source by rudimentary forms of life beneath the Martian surface. On Earth, microbes do this in a range of environments.
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"One of the most exciting developments in the exploration of Mars has been the suggestion of methane in the Martian atmosphere," said University of Aberdeen professor John Parnell, who directed the research.
"Recent and forthcoming missions by NASA and the European Space Agency, respectively, are looking at this, however, it is so far unclear where the methane comes from, and even whether it is really there.
McMahon noted that the team's approach may prove helpful in future Mars rover experiments.
"Even if Martian methane does not directly feed microbes, it may signal the presence of a warm, wet, chemically reactive environment where life could thrive," McMahon said.