Thousands gathered in the rain in the Brazilian capital to support Bolsonaro, who was sentenced to 27 years in prison last year for leading a failed coup d'etat following his narrow re-election loss.

Footage shared online shows crowds with colourful umbrellas and plastic ponchos stunned by a sudden flash of light and rumbling sound.

The fire department told AFP they treated 89 people at the scene, including 47 who were taken to hospital.

Eleven people "required major medical care," the fire department added.

The gathering was organized by Brazilian lawmaker Nikolas Ferreira to demand "amnesty" for Bolsonaro.

The former head of state is incarcerated in the Papuda penitentiary complex in Brasilia.

He suffers from serious health complications related to a 2018 stabbing on the campaign trail and spent a week in hospital in December following surgery for a groin hernia and treatment for recurring hiccups.

Earlier this month he underwent tests after a fall in prison, but no serious injuries were found.