Brazil court rejects election challenge

The head of Brazil's electoral court has rejected a complaint from President Jair Bolsonaro's allies to challenge the presidential election, the incumbent lost by a small margin.

Luiz Inacio Lula da Silva narrowly defeated Bolsonaro in the October 30 runoff election, marking a stunning comeback for the leftist former president and the end of Brazil's most right-wing government in decades.

Lula's margin of victory was less than two percentage points.

Alexandre de Moraes, who also serves as a Supreme Court justice, fined the parties in Bolsonaro's coalition 22.9 million reais ($A6.35 million) for what the court described as bad faith litigation, a court document showed.

On Tuesday, Bolsonaro's Liberal Party (PL) filed a complaint to challenge the outcome of the election claiming some of the electronic voting machines were flawed and those votes should be invalidated, an argument that election authorities met with skepticism.

Under the terms of Wednesday's electoral court decision, political funds for the president's coalition parties were ordered blocked until the fine is paid.

The ruling also ordered an investigation into any misuse of the party's structure and funds by PL head Valdemar da Costa Neto.

In the ruling, Moraes described the challenge as "offensive" to democratic norms, adding that it sought to encourage criminal and anti-democratic movements.

"The ballot boxes generate files that make it possible to identify precisely which equipment they were generated on," the decision read.

"When one of these mechanisms stops working, others replace it, without affecting its traceability and the possibility of identifying ballot boxes."

The complaint had been met with skepticism by election authorities and other political figures who recognised Lula's victory.

The head of Brazil's Senate, Rodrigo Pacheco, said the election result was "unquestionable" while the centre-right Brazilian Social Democratic Party (PSDB) called Bolsonaro's challenge "senseless".

Election experts and political analysts also blasted the election challenge from Bolsonaro as weak on the merits, but said it could still fire up supporters protesting his defeat at the polls.

"Bolsonaro's style is to always go for confrontation, and this challenge is evidently a way to keep his hard-right supporters mobilised," political strategist Luiz Flavio Guimaraes said.

He said the right-wing Liberal Party provided no evidence of fraud when it presented the complaint.

Analyst Andre Cesar at Hold Legislativa consultancy said the challenge provided ammunition for an ongoing protest movement of Bolsonaro's hardcore supporters.

"His arguments are flimsy but this will serve him to keep the most radical of his supporters mobilised, guaranteeing that they will continue to make noise outside army barracks," he said.

Die-hard Bolsonaro supporters have been camped out in front of army bases protesting against Lula's victory which they say was "stolen" by electoral fraud and calling on the military to intervene.

Their numbers have dwindled in recent weeks and there was no immediate sign of an uptick on Wednesday.