Ms Laporte kept the sketches in a safe for many years

The artwork was sold by Genevieve Laporte, who had a secret two-year love affair with the painter in the 1950s.

A work entitled Odalisque was purchased for �315,454 ($575,357), over three times its estimated value, Artcurial auction house said.

The buyer was not identified, the Associated Press reports.

Inscription

Ms Laporte said it was her "mission" to rehabilitate Picasso, who has often been called "arrogant and scornful" in his relations with women.

The 79-year-old hoped the sketches would be purchased by a single buyer.

"They are like a river, where you can't separate water drops," she said last week, saying it made no sense to leave the drawings to relatives.

"It can't be the same," she said. "They can't have the same relationship I have with these drawings."

Ms Laporte first met Picasso in 1944, when she interviewed him for her school newspaper.

"The first time I saw him I thought he was a very kind and lovely man," she said.

Picasso asked Laporte to move in with him in 1953 but she refused

But it was another six years before their affair began. "He was the same age as my grandfather, older than my mother," she explained.

Picasso sketched many pictures of Ms Laporte while on holiday in St Tropez in 1951 at the height of the couple's affair.

Many sketches bear the inscription "For Genevieve".

But Ms Laporte refused to move in with Picasso two years later, shortly after his girlfriend Francoise Gilot had left him.

"His ex-girlfriend leaves one morning, and he asks me to move in to the house the next day," she said. "Would you have gone?"

Ms Laporte married a former member of the French Resistance in 1959 and became an award-winning poet and documentary film-maker.