A cameraman's death poisoned the political climate on Thursday in Rio de Janeiro, where a heavy police presence monitored fresh protests amid claims that radical left parties were paying violent demonstrators.
Amid increasingly tense protests just four months before Brazil hosts the World Cup, Santiago Andrade was struck on the head by a flare thrown by a demonstrator in Rio a week ago, and died of his injuries on Monday.
A 23-year-old man suspected of throwing the flare was arrested in northern Brazil. He faces up to 35 years in prison.
The suspect told police he has already been "asked to participate in protests in exchange for payment".
The most radical protesters, many of them poor or working class, also sometimes receive food and fares to travel to the demonstrations, Caio Silva de Souza said in his police statement made public by tabloid Extra.
Many Brazilians are angry that the cost of living is rising inexorably, services remain poor and yet the country is spending billions on hosting the World Cup in June and the 2016 Rio Olympics.
Critics have suggested that hard-left parties paid disaffected young radicals to turn up and stoke social tension in the run-up to June's World Cup and October elections.
Some leftist marchers responded to that by brandishing a banner reading: "I didn't get a real; I am here for an ideal."
Police estimated the crowd at 500, while organisers said they numbered 2000.
A strong police contingent barred protesters from entering Central Station, the largest railway station in Rio.
De Souza did not say if he had actually received cash but his lawyer indicated some marchers had been offered 150 reais ($A67) to "foment violence" and "destabilise the government".
Protesters have indicated they will keep on marching right up to and during the World Cup, prompting security concerns.
Last year's Confederations Cup in Brazil was marred by huge demonstrations drawing more than a million people nationwide.
However, tournament organisers and world football body FIFA say they have full confidence in an integrated security system across the 12 venues.
