The arrested man said a sketch by Italian painter Guglielmo Caccia, donated to the gallery in 1907 and also stolen in 2012, had been destroyed, the ministry said.
The paintings will be exhibited once again in the National Gallery, which opened in March after nine years of renovation work, as part of celebrations marking the 200th anniversary of the Greek War of Independence in Athens.
“In our new gallery, they will find the place they deserve,” Citizens' Protection Minister Michalis Chrisochoidis told a joint news conference with Culture Minister Lina Mendoni.
“Picasso dedicated the painting to the Greek people,” he said. “There was a Greek man who took it away. There were Greeks who brought it back.”
Mendoni said the Picasso painting bore an inscription from the painter to the Greek people for their fight against fascism.
“That is the reason it was impossible for the painting not only to be sold but also to be exhibited anywhere,” she said.