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Water may have been brought to Earth by asteroids from the outer edges of the solar system, according to scientists analysing samples of rock and dust.

Researchers have been studying material gathered from a distant asteroid called Ryugu by the Hayabusa-2 spacecraft in 2020.

The Japanese space agency, Jaxa's six-year mission was to understand more about the solar system.

In a new paper published in the journal Nature Astronomy, scientists said the samples from the asteroid could show how oceans appeared on Earth billions of years ago.

Experts believe early asteroids may have preserved and delivered water to Earth.

The samples from the Ryugu asteroid are believed to be some of the most uncontaminated Solar System material available for study and appear to show asteroids could have held and brought water to Earth.

"Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth's water," said the study by scientists from Japan and other countries.

Ryugu might also contain organic materials, which means that asteroids may not only have provided Earth with its water, but also helped start very early life on the planet as well.

The Japanese Hayabusa 2 craft touched down on Ryugu, a near-Earth asteroid, in July 2019.

The probe brought to Earth samples of space dust, which have been analysed in labs all over the world.