The skull was found by Italian researchers in Eritrea, in north-eastern Africa, and it remains embedded in the rock where it was found.

The scientists provide details in the latest issue of the journal 'Nature'.

Sarah Griffiths of the BBC's science unit says it could help provide a clearer picture of how and when early humans migrated from Africa to Europe and Asia.

The find falls into a time period when human fossils are exceptionally scarce and is in a geographical area of unique importance.

Clues about early humans

The earliest human ancestors came from Africa and colonised Europe and Asia later on. Exactly when and how this happened remains controversial but what is clear is that this part of northeastern Africa was a channel for the migration of ancient populations.

The Eritrean skull may provide a clearer picture of the first early humans who left Africa for Asia and Europe.

Now the initial report on the skull has been made public, scientists around the world can begin to examine the evidence for themselves.

The correspondent says that, in a field where there are precious few fossils, this is a find that will be talked about and argued about for years to come.