Supporters of former Brazilian President Jair Bolsonaro have broken into the Congress building in the capital, Brasilia. They refuse to accept the former president's defeat in an election held last year.

The crowd breached security barricades and gained access to the congressional building on Sunday. They also invaded the Supreme Court and presidential palace buildings in the neighborhood.

Footage shows people clad in the national flag storming into the Congress building and a plume of what appears to be police tear gas.

Brazilian media report that about 3,000 people were involved in the invasion, with some smashing windows.

Leftist Luiz Inacio Lula da Silva won the presidential runoff in October by a slim margin and took office on January 1.

However, some of Bolsonaro's supporters have refused to accept Lula's victory and have staged protests around federal buildings.

Lula told reporters in Sao Paulo that anyone who stormed the buildings will be found and punished.