Police registered a case of rape against the diplomat, working in the French consulate here, under Section 376 of Indian Penal Code, Nayak said.
The diplomat was detained late last night.
The child's mother, an Indian, reported the case to police with the help of a Bangalore-based NGO after her maid told her that the three-year-and-ten-month-old child was sexually abused, she said.
"When the mother returned home, her domestic help told her that her husband had been in their bedroom with the child for over three hours. She found her child crying and in great pain," Nina said.
The mother immediately took her child to a private hospital at Hebbal which confirmed the sexual assault, she said, adding that the diplomat has been identified as Pascal Mazurier, deputy head of the Chancery in the Consulate of France in the city.
Nina also said the French diplomat is being questioned and further tests were being conducted to ascertain whether the rape had taken place.
She said she has asked the NGO to take the child with her mother to a state-run hospital for examination and submit a report.
DCP (Central) Ravikante Gowda said a case has been filed in connection with the incident and police are still questioning the man. But he has not yet been arrested as the child's medical report is awaited.
Asked about who had lodged the complaint, Gowda said, "A blood relative has filed a complaint." However, he did not disclose the name of the accused.
