Sao Paulo could roll out a COVID-19 vaccine developed by China's Sinovac without approval as Governor Joao Doria pressures Brasilia to issue him a green light.
Health experts on Thursday called Doria's threat empty as no drugs or vaccines can be used legally in Brazil without clearance from health regulator Anvisa.
Still, his statements reveal growing tensions over the vaccine rollout in Latin America's biggest country, with the world's second-highest COVID-19 death toll.
Critics of President Jair Bolsonaro argue he is threatening the independence of Anvisa with political appointees to gain leverage over governors and other rivals.
In a video interview on the news website Metropoles, Doria said Sao Paulo could use the vaccine from Sinovac Biotech based on approval from regulators in other countries.
"Today, there is suspicion Anvisa could suffer political interference from the presidency and could fail to be an independent agency as it should be, as it must be," he said.
He added the state would consider the vaccine appropriate for use if approved by authorities "in the United States, in Europe and, above all, in Asia".
In a statement, Anvisa said that was impossible.
"It is important to clarify that the tacit approval of vaccines by other agencies ... is not foreseen in the law," the regulator said.
"Even after it is approved in another country, Anvisa's approval is necessary."
Doria, a staunch opponent of Bolsonaro, has already ordered the construction of facilities to produce the Sinovac vaccine, which is currently undergoing late-stage trials in Sao Paulo and elsewhere in Brazil.
Bolsonaro, a strident China critic, has frequently dismissed the Sinovac vaccine, known as Coronavac, saying he is concerned about its "origin".
So far, the federal government's principal bet has been on a vaccine being developed by AstraZeneca, though federal health officials have also held discussions with other vaccine developers.
Australian Associated Press
