Embattled Brazilian President Michel Temer has said he will fight allegations that he endorsed the paying of hush money to an ex-politician jailed for corruption.
Opposition politicians took to Twitter and local news channels to call for Temer to resign or be impeached, arguing his government no longer had legitimacy.
"If Temer doesn't fall, he will lead a walking dead administration", said Claudio Couto, a political science professor at Fundacao Getulio Vargas, a Sao Paulo-based university and think tank.
Mr Temer is trying to get pension reforms through Congress that would mean men would have a minimum retirement age of 65, and women 62, and most people would contribute more.
The Sao Paulo stock market's Bovespa index crashed more than 10 per cent after opening, triggering an automatic suspension of trading for 30 minutes.
At the same time, Brazil's currency, the real, hit its lowest recent exchange rate versus the dollar, falling to 3.315 real per dollar.More news: Trump to embark on first overseas trip
Temer has denied any wrongdoing and on Thursday refused to resign.
Globo reported late on Wednesday that Mr Neves had been recorded asking JBS meat-packing company executive Joesley Batista for 700,000 United States dollars (£540,000) to pay for his "Car Wash" defence.
"I will not resign", Temer said in a televised message to the nation after the Supreme Federal Court chose to open an investigation regarding allegations made the previous day that he approved of payments to a former powerful lawmaker to keep quiet.
Globo also reported that Batista had recorded Temer endorsing a bribe to silence former Speaker of the House Eduardo Cunha.
The veteran centre-right politician, who took over a year ago with a promise to restore Brazil's stability after the impeachment of leftist president Dilma Rousseff, remained defiant.
A major newspaper in Brazil, O Globo, is reporting that Temer was caught on tape discussing bribery payments.More news: VW's GTI on the way up!
Rousseff and her leftist allies accuse him of having engineered her impeachment and his own rise to power a year ago in what they say amounted to a coup d'etat. Neves, who almost won the presidency in 2014 and planned to run again next year, has denied wrongdoing. To the revelation of a scheme to keep the judges from pressuring Batista, Temer asks "are you holding both of them back?", which Batista confirms before the president says the equivalent of "excellent, excellent". According to the Globo report, Batista secretly recorded the conversation with Temer and gave it to justice officials as part of plea bargain negotiations.
Temer is deeply unpopular but has been able to rely on a dominant alliance between his centre-right PMDB party and the PSDB Social Democrats, along with a coalition of smaller parties. The tapes record Temer expressing his support for the payout of hush money to imprisoned politician Eduardo Cunha, and Neves soliciting 2 million reais (nearly $600,000) to pay for his own defense against corruption charges.
The culture minister, Roberto Freire, resigned Thursday and Brazil's media was rife with reports of other ministers threatening to exit.
"This climate isn't one in which to work", Rodrigo Maia, president of the lower chamber, told Globo News after adjourning legislators.
It seems Brazilian politics just can't catch a break as President Michel Temer becomes embroiled in a corruption scandal of his own.
Globo's report represents the latest in numerous scandals that have plagued Temer, whose approval ratings are hovering around 10 percent.More news: Rex's Railroad Spike Teeth Were a Pulverizing Machine
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