A Brazilian art restorer has discovered a new layer hidden in a centuries-old painting of the Greek god of fertility Priapus by French artist Nicolas Poussin - the deity's erect penis.

"They hid the phallus of Priapus. It's what we call adjustment for modesty, and it's not uncommon," said Regina Pinto Moreira, quoted in Tuesday's edition of the Folha de Sao Paulo newspaper.

She suspects the cover-up was made in conservative Catholic Spain in the 18th century.

Ms Moreira, who worked as an master art restorer at the Louvre in Paris for some 30 years, spent eight months alongside two French experts restoring Poussin's large 1634-1638 painting Hymenaios Disguised As A Woman During An Offering To Priapus.

The 3.71-metre by 1.66-metre artwork depicts Hymenaios, the Greek god of marriage ceremonies, dressed as a woman and dancing with Priapus, who was traditionally depicted with an erect penis.

The painting however once belonged to the Spanish royal family, and Ms Moreira says she thinks this was when the post-production modesty came in.

Removing layers of dirt, dust and paint specks that accumulated over more than three centuries cost 150,000 euros ($257,500).

The artwork will be put on display at Sao Paulo's grand Museo de Art on September 8.

- AFP