Brazilian President Jair Bolsonaro said on Thursday he will know "in the next few hours" if he has contracted the new coronavirus after a top aide tested positive for the disease following a trip on which both met with US President Donald Trump.

The 64-year-old Bolsonaro revealed the news in a live Facebook transmission in which he was wearing a face mask.

"I'm using a mask because when we returned from our recent trip to the United States, one of the people that traveled with us had tests in Sao Paulo and it came up positive," said Bolsonaro.

The far-right leader's communications chief, Fabio Wajngarten, tested positive for COVID-19 after last weekend's trip to the US during which both men met with Trump at his Florida resort.

Wajngarten was photographed standing side-by-side with Trump.

"Today we collected all the samples and in the next few hours we will have the result," said Bolsonaro.

He cancelled a scheduled trip on Thursday to the city of Mossoro, in northeastern Brazil, and his office said he had no other official events on his daily agenda.

Bolsonaro had previously sought to downplay the coronavirus pandemic, saying its severity had been "overstated."

Earlier on Thursday, his son Eduardo revealed on Twitter that Bolsonaro had been tested for the new coronavirus but was not "exhibiting any symptoms of the disease."

Trump has said he was "not concerned" about contracting the virus and the White House said he did not need testing.

Trump and Vice President Mike Pence "had almost no interactions with" Wajngarten, White House press secretary Stephanie Grisham said in a statement.

They "do not require being tested at this time," she said, explaining that US government guidelines do not recommend testing for people without symptoms.

Eduardo Bolsonaro, who also accompanied his father to the United States, said he was undergoing testing as well.

The president said another member of the Brazilian delegation had been tested with the results coming back as negative, but didn't reveal who that was.

The Brazilian delegation also included Foreign Minister Ernesto Araujo, who cut short a subsequent trip to Washington on Thursday to return to Brazil. He would follow all current protocols on the virus, his office said.

Bolsonaro also on Thursday asked his backers to call off a planned demonstration on Sunday to show their support for him in his clashes with parliament and the judiciary.

He suggested suspending it "for a month or two."

According to local press, two groups involved in organizing the demonstration responded to Bolsonaro's call by canceling it.

Brazil has 77 confirmed cases of new coronavirus and another 1,400 suspected cases, according to health ministry figures.

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