President Michel Temer of Brazil has denied a newspaper report that he approved payments to silence a possible witness in a corruption inquiry.
He was accused of authorising illicit payments to a jailed former speaker of the lower house of the Brazilian parliament, Eduardo Cunha.
Cunha was sentenced in March to 15 years in prison for corruption, money laundering and tax evasion.
The accusations against Mr Temer were made by O Globo newspaper.
The allegations have sent shockwaves across the country and one politician has already filed an impeachment request against the president, the BBC’s Julia Carneiro reports from Brazil.
A demonstration calling for Mr Temer to resign was reported in the city of Sao Paulo on Wednesday evening.
Mr Temer, a former law professor, played a key role in the impeachment proceedings against his predecessor, President Dilma Rousseff, last year.
As vice-president, he replaced her after she was impeached and removed from office.
O Globo says it has obtained recordings of a discussion between Mr Temer and an official from the giant meat-packing company JBS.
The newspaper says the tapes were presented in plea bargain negotiations between prosecutors and two JBS executives.
Mr Temer’s office says the allegations are false and is calling for them to be thoroughly investigated.
“President Michel Temer has never requested payments to obtain the silence of former MP Eduardo Cunha,” it said.
“He did not participate in, nor did he authorise, any movement with an aim to avoid that the former congressman make a plea bargain deal or co-operate with justice.”
It confirmed that a meeting with a JBS executive had taken place in March but said “there was nothing in the dialogue that would compromise the President’s conduct”.