Brazil’s congress has given President Jair Bolsonaro an ultimatum to release the results of his coronavirus tests within 30 days, amid widespread speculation that he has been infected with Covid-19.

“Brazil needs the truth! Was the president infected?” said the motion proposed by the leftist congressman Rogério Correa and agreed by leaders of the chamber of deputies.

The motion noted that 23 people who accompanied Bolsonaro on a visit to the US in March had since tested positive. Several of them attended a dinner at Donald Trump’s Mar-a-Lago resort.

Since then, Bolsonaro has refused to share the outcome of two coronavirus tests he underwent – even refusing a freedom of information act request – leading to widespread speculation that he had contracted some form of Covid-19.

In March, he said that his athletic background meant that if he did catch coronavirus he “wouldn’t feel anything or at the very worst it would be like a little flu or a bit of a cold”.

Bolsonaro has attacked social isolation measures and state governors who introduced them, ignoring the advice of his own health minister, Luiz Mandetta, to mingle with supporters. Last week he was filmed shaking an elderly woman’s hand after wiping his nose on the back of his wrist.

“If it shows he had the disease it shows how irresponsible his behaviour was and how he put these people’s lives at risk,” said Maurício Santoro, a professor of international relations at the State University of Rio de Janeiro. “It creates a whole political discussion about truth and transparency.”

For more than a week, Bolsonaro has reportedly been on the verge of sacking Mandetta for indirectly criticising his behaviour and the mixed messages the government has sent out.

On Wednesday Mandetta appeared to accept that he would soon be out of the job, telling reporters that Bolsonaro wanted a different approach from his own, which was “based on the information that we have, based on science”.

Brazil has more than 28,000 confirmed coronavirus cases and 1,736 deaths.

If the presidency minister, Jorge Oliveira, fails to comply with congress’s order, he could be charged with a “crime of responsibility” but there is no direct threat to Bolsonaro’s mandate, said Eloísa Machado, a professor of constitutional law at São Paulo’s Getúlio Vargas Foundation. Still, the move “damages the president’s position against isolation”, she said.