The chances of finding alien organisms have been boosted by the discovery of hundreds of “water worlds” capable of supporting life.

New analysis by Harvard University estimates that one in three “exoplanets” outside our solar system that are larger than Earth are likely to contain an abundance of water.

The scientists say the planets that are two to four times bigger than Earth that have the best chance of supporting life.

Analysis of data from the exoplanet-hunting Kepler Space Telescope and the Gaia mission indicates half their weight may be water - either flowing or frozen.

In comparison, the amount of water on Earth makes up just 0.02 per cent of its complete mass.

Lead researcher Dr Li Zeng, said: "It was a huge surprise to realise that there must be so many water-worlds."

Exoplanets were first discovered in 1992 and since then about 4,000 have since been confirmed to exist.