Lawyers for Brazil's former President Luiz Inacio Lula da Silva petitioned the United Nations on Thursday with allegations that his human rights had been violated in a corruption investigation.
Lula, once a leftist icon and Brazil's most influential politician, is under investigation for allegedly benefiting from a kickback scheme at state-run oil firm Petroleo Brasileiro SA, or Petrobras.
British lawyer Geoffrey Robertson, who has defended boxer Mike Tyson and WikiLeaks founder Julian Assange, joined Lula's Brazilian lawyers in filing the petition to the U.N. Human Rights Committee.
As president from 2003 to 2011, Lula campaigned to help Brazil win the 2014 World Cup and next month's Summer Olympics.
Companies such as Odebrecht SA are accused of overcharging Petrobras for work and passing kickbacks on to politicians. They are also being investigated for graft on World Cup stadium contracts and Olympic venues.
Odebrecht said it was cooperating with authorities. Lula said he was innocent and was the victim of a witch hunt.
The 39-page petition lashes out at federal Judge Sergio Moro, who presides over most cases in the Petrobras investigation and has ordered the arrest of dozens of high-level construction executives in recent years.
"Lula is a victim of abuse of power by a judge, with the complicity of prosecutors and the media," the petition said.
Lula hopes the U.N. "will not only provide some compensation for the violation of his rights but also help future governments draft laws and procedures that can improve the fight against corruption while protecting the basic rights of suspects."
Moro allowed prosecutors to detain Lula for questioning at an airport in Sao Paulo in March. The petition said that was illegal. Moro did not immediately respond to a request for comment on the petition, but he has repeatedly said his actions were legal.
The Supreme Court took over the Lula investigation later in March after Moro released a wiretap of a conversation between Lula and then-President Dilma Rousseff. Moro said the phone call was evidence Rousseff was appointing Lula to her Cabinet to shield him from prosecution.
Rousseff was since impeached on unrelated charges of manipulating public accounts; a final Senate vote is pending. The Supreme Court has again given Moro jurisdiction over Lula's case.