The 21cm (8.5 in) long prints are thought to date as far back as 30,000 years and the archaeologists say they were left by a child tripping in the mud.

"The footprint in the clay is extremely clear," said palaeontologist Jean-Luc Guadelli. "You can see the five toes, the sole and a skid-mark."

The prints were found in the Chauvet cave in the Massif Central in central France which was discovered in 1994.

Closest ancestors

The site has become world-renowned as one of the richest pre-historic sites in terms of cave paintings and other evidence of man's immediate ancestor, homo sapiens sapiens.

Four prints in all were discovered on the clay floor - one of the right foot, three of the left.

They are thought to have belonged to a young male about 1m 30cms (4ft 4in) high and aged between eight and 10 years old.

Older footprints have been found in South Africa, among other places, but they belong to earlier ancestors of the human race.

Exotic animals

The prints were discovered last month by a team of experts who also found another 30 cave paintings in the caves 500 metre-long galleries.

That brings the total to almost 450 paintings, depicting 14 different species including mammoths, leopards, lions, rhinoceros and other exotic animals that have long since left the fields of France.

The site is considered so important that it will never be open to the public.

It is also at the heart of a dispute between the team that discovered it and the French Government.