John Peter Moore worked with Dali for 20 years

John Peter Moore, 85, who was Dali's assistant for 20 years, was accused of manipulating The Double Image of Gala, which was stolen in 1974.

The painting turned up after Dali's death in 1989 but there was no explanation of where it had been.

Moore must also pay additional costs for repairing and restoring the piece.

The compensation, imposed by a Catalan court, will be paid to the Gala-Salvador Dali Foundation.

Moore's wife, Catherine Perrot, was also convicted on the same charge of "damaging the moral rights of the author".

They were accused of reducing the size of the painting and renaming it Dali Painting Gala.

Gala was Dali's wife and the inspiration for the painting.

The mystery surrounding the painting's disappearance from New York's Knoedler Gallery has never been cleared up and Dali was paid $125,000 (�68,210) insurance money.

Despite extensive searches by Interpol and the FBI it did not turn up until 1999, where it was discovered hanging in the Perrot-Moore's Art Center in the town of Cadaques, in the north-east of Spain.

Moore's home was searched at the time and 10,000 fake Dali lithographs were found, although he was not charged because of his age.

Moore was responsible for marketing Dali's works through the 1970s, and was instrumental in building up the Spanish artist's fortunes.