Brazilian President Luiz Inacio Lula da Silva has fired the army commander, General Julio Cesar de Arruda, a source with knowledge of the matter says.
The firing of Arruda, who had been commander since December 28, was reported earlier on Saturday by Brazilian newspaper Folha de S Paulo and TV network Globonews.
His replacement will be General Tomas Miguel Ribeiro Paiva, army commander of the southeast, the source said.
The official website of the Brazilian armed forces said on Saturday that Arruda had been removed as head of the army.
Lula said this week that intelligence services failed on January 8, when government buildings in Brasilia were stormed by supporters of former president Jair Bolsonaro.
Previously, Lula said he suspected collusion by "people in the armed forces" in the unrest, during which several thousand Bolsonaro supporters invaded and ransacked the Congress building, the presidential palace and the Supreme Court.
Arruda had attended a meeting with Lula on Friday, accompanied by the commanders of the navy, Marcos Sampaio Olsen, and air force, Marcelo Kanitz Damasceno.
Defence Minister Jose Mucio Monteiro told reporters after the meeting that the January 8 riots were not the main discussion topic but added that any involvement of military personnel in the riots would be punished.
Lula has said recently that his government would purge hardcore Bolsonaro loyalists from the security forces.
Many of the demonstrators who rioted in Brasilia called for a military coup to restore Bolsonaro to power.