The UN human rights committee said on Thursday that corruption proceedings against former Brazilian President Luiz Inacio Lula da Silva that led to his imprisonment and prevented him from running again for office in 2018 violated due process.
The finding follows a decision last year by Brazil's Supreme Court to annul his corruption conviction, which enabled him to launch a campaign for October's presidential election.
Lula is currently the frontrunner for that ballot ahead of far-right incumbent Jair Bolsonaro.
"Procedural violations rendered Lula's prohibition to run for president arbitrary and therefore in violation of his political rights, including his right to run for office," a statement on behalf of the committee of independent experts said.
Lula filed a complaint to the committee, which oversees countries' compliance with the International Covenant on Civil and Political Rights, about how he was brought to trial in Brazil's biggest ever corruption investigation known as 'Car Wash'.
It found that wiretaps during the probe and their disclosure to the media violated his right to privacy while actions by the judge and prosecutors violated his right to presumption of innocence, the statement said.
It urged Brazil "to ensure that any further criminal proceedings against Lula comply with due process guarantees and to prevent similar violations in the future".
Lula governed Brazil from 2003 until 2010 and oversaw a period of dramatic economic growth - driven by a commodity boom - that helped lift millions out of poverty.