An 80-year-old French man is recovering in a state of shock in hospital after being freed from a year locked in a laundry room by a wife half his age and her alleged lover.

French paramilitary police rescued the unnamed man from his home in the village of Arrou, south-west of Paris, on Wednesday, blinded, malnourished and physically abused by the ordeal at the hands of his own family.

A judicial source says the man is conscious and lucid in hospital but does not yet want to speak to anyone.

"The victim suffered violence and ill-treatment," local gendarme commander Bruno Arviset said.

"The man ate twice a day, mostly pastries that were past their sell-by date."

His wife, 45, was jailed pending trial after being charged with physical abuse, illegal detention and taking advantage of a vulnerable person.

Her alleged lover and her son have been released on bail after being charged with complicity with kidnapping and failing to report the abuse.

Investigators suspect the man's family had a financial motive as around 500,000 euros ($721,000) had been taken from the man's bank accounts in recent months.

Deputy prosecutor Fanny Floquet says that when police arrived at the couple's home, the wife had initially said that her husband was abroad.

"The wife finally led them to a small room in the house away from rooms used to live in and opened a locked door in front of the gendarmes," Ms Floquet said.

Prosecutors says one of the woman's young children originally alerted them to the case.

Ms Floquet says the child "said there was an old man at home who was dirty, who stole food and who was abused because in particular he could make [the child's] mother angry".

Social services has now taken the child into care.

- AFP