A debate about sexual violence in Brazil sparked by a lawmaker's comments on the floor of Congress has spread beyond government chambers, triggering a national debate about rape and sexism in the South American nation.

Opposition congressman Jair Bolsonaro told Maria do Rosario Nunes in Congress he would not rape her "because she was not worth it."

Then, he said it again.

"Stay here Maria do Rosario!" he yelled during a parliamentary session on Dec 9, the eve of International Human Rights Day.

"It's been several days since you called me a rapist, and I said that I did not rape you because you weren't worth it," the 59-year-old retired soldier yelled at Rosario Nunes.

It was not clear under what circumstances Nunes called him a rapist, as alleged.

Angry Brazilians also took to social media to voice their disgust at his comments, while the United Nations called his comments "unacceptable."

Rosario Nunes, a close ally of leftist President Dilma Rousseff, filed a complaint, accusing him of libel and slander, and charged him with public incitement to rape.

"I am not doing it for me, but for all Brazilian women, because no one deserves to be raped. I do not accept in Parliament or anywhere, the incitement to rape," said Rosario Nunes, former minister for Human Rights.

Unrepentant, Bolsonaro said he would not ask for her forgiveness and pressed on with his comments.

"She isn't worth it, because she's ugly, she's not my type. I would never rape her," he told Zero Hora newspaper.

The right-wing Bolosnaro is known for his outspoken comments and frequent anti-leftists attacks.

He blamed Rosario Nunes for unfairly accusing him, but insisted again he was not interested in her because of her looks.

"Suddenly, she was calling me a rapist, and she repeated this offence," said Bolsonaro.

"It was an unfair verbal attack, I responded that I was not a rapist and that if I was, I wouldn't rape her because she wasn't worth it," he said in an article in Folha de Sao Paulo newspaper.