Divers have discovered a long-submerged wall some 7,000 years old under the sea off western France, scientists said Thursday.

Some 120 metres long, it was found off the Ile de Sein in Brittany along with a dozen smaller manmade structures from the same period.

"This is a very interesting discovery that opens up new prospects for underwater archaeology, helping us better understand how coastal societies were organised," Yvan Pailler, professor of archaeology at the University of Western Brittany, told AFP.

He co-authored a study on the find, published in the International Journal of Nautical Archaeology.