An original cover painting from the 1963 comic book Asterix and Cleopatre was to go under the hammer on Sunday despite a legal challenge from the artist's daughter.
The famous gouache, showing a reclining ancient Egyptian ruler and the two Gaulish heroes Asterix and Obelix was to be sold by the Brussels auction house Millon.
Measuring 32 by 17 centimetres, it is expected to fetch between 400,000 and 500,000 euros -- but the sale was almost blocked by the daughter of the late French illustrator Albert Uderzo.
Sylvie Uderzo argued that if her father had given the painting away he would have signed and dedicated it, and thus the painting must have been stolen.
Millon insists that it is selling the work on behalf of the son of a man who was given it more than 50 years ago by Uderzo, the co-creator of the Asterix series who died in 2000.
The daughter lodged a complaint with Belgian prosecutors on November 27 but, according to a letter seen by AFP, they found no grounds to suspect a crime had been committed.
Sylvie Uderzo's lawyer Orly Rezlan had warned that any buyer of the cover painting could be prosecuted for receiving stolen goods, an idea rejected by the auctioneers.
"During his lifetime, Albert Uderzo publicly stated that he would oppose the sale of any drawing that did not include his dedication," the lawyer argued last week.
Uderzo, she said, had always said of original plates without dedications that "If you bring one to me, I'll dedicate it to you".
But Arnaud de Partz, director general of Millon Belgium, argued that many other non-dedicated pieces by Uderzo have already been put up for public auction.
And the house has produced a photograph in which a man presented as the owner of the drawing shares a meal with Uderzo and his wife at a hotel in Normandy in the late 1960s.
"We showed this photo to Sylvie Uderzo to show her that the sellers' father knew her father well," de Partz said.
The story Asterix and Cleopatre appeared as a serial in Pilote magazine in 1963 and was bound as the sixth book length adventure in the series in 1965.
The cover art parodies the poster for the 1963 Hollywood epic "Cleopatre", then the most expensive ever made, with Uderzo's Cleopatre in the same pose as its star Elizabeth Taylor.
Asterix, the plucky Gaulish hero, stands in for Rex Harrison's Julius Caesar and his portly sidekick Obelix for Richard Burton's Marc Antony.
In recent years art from the original editions of beloved French and Belgian comic book successes like Asterix or Tintin has attracted wealthy collectors and investors.
In February, the original 1942 cover art of "Tintin in America" by Belgium's Herge, was sold in Paris for 2.16 million euros.
But the estates of the late comic book writers and illustrators fiercely guard the rights to what have become global brands, and several sales have attracted controversy.