Former Brazilian president Jair Bolsonaro on Wednesday denied all involvement in anti-government riots by his supporters in January as he appeared before federal police.

The far-right leader is being investigated for his alleged role in masterminding and instigating the riots that sought the overthrow of his successor, President Luiz Inacio Lula da Silva.

Bolsonaro, who returned to Brazil in late March after spending three months in the US state of Florida, was questioned for more than two hours at the federal police headquarters in Brasilia, but left in a vehicle with tinted windows without speaking to reporters.

Shortly afterward, Bolsonaro's spokesman Fabio Wajngarten told the press that the former president had "repudiated all the unfortunate events that happened in Brasilia" on the day of the riot.

One reason the investigation was launched was because two days after the riot, Bolsonaro shared a video to social media of a prosecutor contesting the validity of Lula's victory.

Bolsonaro's lawyer Paulo Bueno said the president had been under the effect of medication and had just been admitted to hospital when he shared the video.

"The sharing was so accidental that he did not mention it afterward and soon deleted it," said Bueno after the hearing.

Lula, who previously led Brazil from 2003 to 2010, narrowly beat Bolsonaro in a fractious, divisive election last October.

Thousands of Bolsonaro's supporters stormed Congress, the Supreme Court and the presidential palace in Brasilia on January 8, a week after Lula took office.

In scenes reminiscent of the January 6, 2021 riots in Washington by supporters of ex-president Donald Trump -- Bolsonaro's political role model -- they trashed offices, smashed windows, vandalized artworks and called for the military to intervene to oust Lula.

Some 1,800 people have been arrested.

Numerous investigations

Bolsonaro left Brazil for Florida on December 30, two days before he was due to hand over the presidential sash to Lula.

On January 13, Supreme Court judge Alexandre de Moraes opened an investigation into Bolsonaro's alleged involvement in the January 8 rampage, in which rioters easily broke through a security cordon.

A parliamentary committee of inquiry is due to be set up soon in Congress to shed light on the events of January 8.

Former army captain Bolsonaro was previously interviewed by police on April 5 in relation to an accusation that he tried to illegally import millions of dollars worth of jewelry gifted by Saudi Arabia.

A source close to the former president told AFP that he denied that accusation.

Bolsonaro is the subject of at least 16 other investigations in which, if found guilty, he could be sentenced to prison or disqualified from politics.