A restraining order has been issued against Brazilian former attorney general Rodrigo Janot after he admitted carrying a gun inside the country's top court to kill one of the judges.

Janot, 63, served as chief public prosecutor from 2013 to 2017.

He led the prosecution for corruption cases against ex-presidents Michel Temer, Dilma Rousseff and Luiz Ignacio Lula de Silva.

He has been barred from being within 200 meters of members of the bench and banned from entering any tribunal building in the South American country.

The former attorney general admitted in an interview that he entered the Supreme Court building in Brasilia in May 2017 to kill a judge who had allegedly smeared his daughter with an untrue allegation.

Janot was quoted by a local publication as saying he was going to kill the judge and then kill himself. But in the end he abandoned the action when he found himself alone in a room in the court building.

"I was alone, and it was the hand of God (that stopped me)," Janot was quoted as saying.

It has been reported that police searched his home to remove his weapons and take his gun license away.

(With input from agencies)