A retired electrician and his wife who kept 271 works of art by Picasso in their garage for close to 40 years have gone on trial in France accused of possessing stolen goods.

Pierre Le Guennec, 75, says the artist and Picasso’s wife, Jacqueline, gave him the oil canvases, drawings and Cubist collages when he was doing work on the last property they lived in before Picasso died in 1973.

But some of the artist’s heirs suspect otherwise and filed a complaint against the couple, who were charged in 2011.

“Picasso had total confidence in me. Maybe it was my discretion,” Le Guennec told the court in the south-eastern city of Grasse at the start of the three-day trial. “Monsieur and madame called me ‘little cousin’.”

He said that one day Jacqueline gave him a box with the 271 works of art inside. “She told me ‘this is for you’,” he said.

When he got home, he looked inside and found “drawings, sketches, crumpled paper”.

He said he and his wife, Danielle, did not look through everything. Asked by the judge whether he wasn’t a little curious, he responded: “No.”

He said: “I didn’t have in mind that they were works of art, they were essays, torn bits, it didn’t grab me. It’s not as if I saw a painting, it’s not the same, it’s not the same reaction.”

He put the present in his garage and discovered it again years later, in 2009. But when he went to Paris the following year to get the works authenticated at the Picasso Administration, the artist’s heirs filed a complaint.

Picasso’s son Claude, who runs the administration, is one of the plaintiffs in the case. Others include Claude’s sister Paloma, half-sister Maya, two grandchildren, and Jacqueline’s daughter Catherine Hutin-Blay.

Jean-Jacques Neuer, Claude Picasso’s lawyer, accused Le Guennec in court of being the cover for “a case of international artwork laundering”. He said: “These stolen works were given to him because he had had ties with Picasso.”

Le Guennec said earlier that he made lists of the artworks with the help of his brother-in-law who had a gallery, before presenting the collection to the Picasso Administration in 2010. But Neuer accused him of never having made any such lists, which he said were too detailed for someone who knew little about art.

In one example cited by the lawyer, Le Guennec said a small pencil drawing had similarities with a 1915 painting of a harlequin exhibited at the Museum of Modern Art in New York.

The defendants’ lawyer, Charles-Etienne Gudin, has said there were only a dozen works of value and that the rest was “very mediocre”, insisting that Picasso never tried to sell them.

He said it would have been extremely difficult for anyone to steal from Picasso, as the artist had “an amazing memory” and his property was protected like a fortress.