Brazilian rapper MV Bill added his voice to a chorus of criticism of President Jair Bolsonaro for downplaying the gravity of the COVID-19 pandemic in a video clip that urges people to protect themselves.

His rap "Quarantine" recorded in the isolation of his home and posted on social media warns that contagion could be explosive in Brazil's crowded "favelas" or slums, such as Rio's City of God where he was born, some with no running water.

Seeing that many Brazilians including their president were not taking the virus seriously motivated his song, he told media by email on Saturday.

"The World Health Organization warned, people paid little heed, head of state downplayed, delayed, they lost time on things that do not matter," he rapped.

COVID-19 is not "a small cold" as Bolsonaro has claimed and more Brazilians will become infected due to the leader's "ignorance" and "arrogance," the singer said.

"Take care, protect yourselves ... there will be no room in the intensive care units," he warned.

The 46-year-old rapper lives next to City of God, a sprawling complex of slums made famous in a hit 2002 movie of the same name and where the first case of coronavirus in Rio's favelas was reported last weekend. 

Armed gangs and militias in the slums have imposed strict curfews and are stopping outsiders from entering to stop the virus spreading.

Confirmed cases in Brazil trebled to 3,417 in the last week, with 92 deaths so far, according to the Health Ministry.

Sao Paulo and Rio de Janeiro, Brazil's two most populous and most affected states, have shut down non-essential business and public gatherings to slow the spread of the virus, their authorities at odds with Bolsonaro who has called the pandemic a "fantasy" that was exaggerated by the media.

Like U.S. President Donald Trump, the Brazilian president has advocated reopening of activities to get the economy moving while minimizing the need for social distancing urged by public health experts.

MV Bill said Brazil's favela inhabitants would not be able to quarantine themselves because they had to work for a living and go to get food as no one was going to deliver to the slum.

The economy must continue working for those with precarious incomes. "We do need to think about the economy, but we can't condemn people to death," he said.

"What worried me the most in this pandemic is the lack of information of people who still don't believe how lethal this virus is," he said by email. "Even with the example of Italy, there are still people who are ignoring it."