Brazilian police raided the Rio de Janeiro state governor's official residence Tuesday as part of an investigation into the alleged embezzlement of funds to build field hospitals for coronavirus patients.
Governor Wilson Witzel, however, condemned the raid as "political persecution" by President Jair Bolsonaro's government.
Federal police also raided Witzel's former home and several other targets in Rio de Janeiro and Sao Paulo, on suspicion that a "corrupt network... embezzled public funds allocated to respond to the public health emergency caused by the coronavirus," they said in a statement.
Of the nine field hospitals that were supposed be built to avoid the collapse of the Rio state health system, just three have been completed so far.
Witzel denied wrongdoing.
The governor, who has clashed with Bolsonaro repeatedly -- including over the president's dislike of the coronavirus stay-at-home measures he has implemented -- said he was being targeted for political reasons.
Bolsonaro, who has downplayed the virus, regularly lashes out at state governors' stay-at-home policies, saying they are needlessly hurting the economy.
"What happened to me is going to happen to other governors who are considered enemies," Witzel told a news conference.
"I'm not going to hang my head... and I won't stop fighting against this fascism, this new dictatorship of persecution in our country."
Speaking outside the presidential palace, Bolsonaro sent his "congratulations to the federal police" for the raid, with a smile.
The politically charged case comes as the number of coronavirus infections has exploded in Brazil.
The country of 210 million people now has the second-highest caseload in the world, after the United States, and has registered more than 23,000 deaths from COVID-19.
Experts say under-testing means the real figure is probably far higher.
Witzel, who was himself diagnosed with COVID-19 last month, was a Bolsonaro ally during the latter's 2018 presidential campaign.
But the pair had a falling out, and Witzel has now emerged as a potential rival when Bolsonaro seeks re-election in 2022.
Bolsonaro recently called Witzel a "pile of manure" during a cabinet meeting.
The video of that meeting became public when it got swept up in a separate investigation into allegations that Bolsonaro obstructed justice to protect his inner circle from federal police probes.
Investigators are looking at whether Bolsonaro improperly fired or pressured the justice minister, federal police chief and head of the federal police in Rio, all three of whom recently lost their jobs.