Pierre Le Guennec, Picasso's former electrician, claimed that artist's second wife gave his family a trunk full of art they kept untouched until they decided to put their affairs in order for their children.
Picasso's family learned of the works only recently when the electrician and his wife contacted the Picasso Administration to have the works authenticated.
Picasso's son and other heirs filed a suit for illegal possession of the works, and police raided the electrician's French Riviera home last month to question him and his wife and confiscated the disputed artworks.
"When Picasso made just a little drawing on a metro ticket, he would keep it," said Jean-Jacques Neuer, a lawyer for Picasso's estate. "To think he could have given 271 works of art to somebody who isn't even known among his friends is of course absurd."
The estate administrators considered that the works might be fake, but they ruled that out because of the expertise, variety of techniques and use of certain numbers in the works that no imitator was likely to have known.
An investigation continues to determine if the couple obtained the artwork legally.
The Art Loss Register, which tracks stolen, looted or missing art, now listed 702 stolen Picasso pieces. Picasso is the most-listed artist in its database of 214,000 art pieces.
The Associated Press Contributed to this report.