Brazilians critical of their government's ambiguous response to a surging coronavirus pandemic dug 100 graves and stuck black crosses in the sand of Rio's Copacabana beach today in a tribute to the nearly 40,000 people who have died so far.

The graves were dug overnight on the beach opposite the ritzy Copacabana Hotel in a protest mounted by non-governmental organisation Rio de Paz.

Brazil has become a major epicentre of the coronavirus pandemic, with 39,680 deaths and over 770,000 confirmed cases as of Wednesday, the world's worst outbreak after the United States.

Far-right President Jair Bolsonaro has downplayed the gravity of the pandemic and pushed local governments to lift quarantine measures, sending contradictory signals to Brazilians on whether to use masks and practise social distancing.