LIMA: Authorities in Peru said on Tuesday they were investigating a woman accused of cutting off her partner's penis with a kitchen knife as he slept.

"We are awaiting the results of the investigation to determine the motive and circumstances of the events," Darinka Lossio, a prosecutor with the northern city of Chota, told Agence France-Presse (AFP) of the weekend attack.

Local media, citing police reports, said the 39-year-old woman had argued with her partner after he returned home drunk, believing he had been unfaithful. The attack then allegedly took place after he fell asleep.

"He had a traumatic amputation; he has been given medical care and will receive psychiatric support," a medical source told AFP.

The prosecutor said the woman remained free, as she was taking care of the couple's three-month-old baby.

"We are outraged; we want justice. My nephew's penis was cut off," the man's uncle told local media.

The story echoes the world's most famous tale of penile amputation, when Ecuador-born Lorena Bobbitt cut off her husband's member as he slept, after he raped her, in the United States in 1993.