With these findings, the team revisited the data from NASA's Deep Impact Mission of 2005, which carried an instrument similar to M3.

The Deep Impact Probe observed the moon for a week June 2-9, 2009.

'This data, along with some laboratory tests carried out from samples brought from Apollo missions, confirmed that the signature is genuine and there is a thin layer of surface mineral which contains traces of hydroxyl and water molecules,' ISRO reiterated.

The M3 observations are strengthened by results obtained from the analysis of archived data of lunar observation in 1999 by another NASA mission, Cassini, on its way to Saturn. This data set also revealed signatures of both OH and H2O absorption features on the lunar surface.

The NASA payload also found water molecules and hydroxyl at diverse areas of the sunlit region of the moon's surface, but the water signature appeared stronger at the moon's higher latitudes.

'We've made a very important step with this discovery, and now there are some very important steps to follow up on,' Pieters said.

Crediting ISRO for its role in the findings, Pieters said: 'If it were not for them (ISRO), we would not have been able to make this discovery.'

Scientists have speculated that water molecules may migrate from non-polar regions of the moon to the poles, where they are stored as ice in ultra-frigid pockets of craters that never receive sunlight.

Though the abundances are not precisely known, about 1,000 water molecule parts per million could be in the lunar soil, the paper noted.

'Harvesting one ton of the top layer of the moon's surface will yield as much as 32 ounces of water,' scientists involved in the discovery said.

Chandrayaan project director M. Annadurai said the discovery of water on the moon was one of the scientific achievements of the country's maiden lunar mission.

'The baby has done its job by finding water on the moon,' Annadurai told IANS here.

The scientific feat has been termed a landmark event in international space cooperation between India and other countries.

'It is one of the milestones. We have to quantify it. It was a combined team effort. Finding out presence of water or ice has been one of the mission's scientific objectives apart from terrain mapping and mineral mapping,' Annadurai recalled.