Police in Brazil arrested a close ally of President Michel Temer on Monday on suspicion of obstruction of justice for allegedly trying to block plea bargain deals that could further sink the country's scandal-plagued administration.

Geddel Vieira Lima was a minister for legislative affairs until November when he was forced to resign after another minister accused him of influence peddling. He has been a close friend of Temer's for decades and is implicated in a series of corruption scandals.

Federal prosecutors said in a statement that Lima tried to silence former lower house Speaker Eduardo Cunha and broker Lucio Funaro, who worked as fundraisers for Temer's centrist Brazilian Democratic Movement Party. Prosecutors accuse Lima of paying hush money.

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In his decision ordering Lima's arrest, federal judge Vallisney de Souza Oliveira said he could be hiding up to $6m in alleged bribe money from Funaro.

Lima's attorney did not respond to calls from The Associated Press seeking comment.

The probe focused on Lima's time as vice president of state-run bank Caixa Economica Federal between 2011 and 2013, when investigators believe he fraudulently channelled funds to politicians.

Prosecutors allege that Lima ensured Cunha and Funaro received bribes and that he repeatedly called Funaro's wife to ask whether he intended to strike a plea bargain.

The crisis deepens for Temer

Temer, whose popularity is at single-digits, is already at risk of being suspended from office if the lower house authorises a corruption investigation against him. Suspension would require a two-thirds supermajority to send the case to the supreme court, with a vote expected in late July.

Prosecutor General Rodrigo Janot accused Temer of receiving a 500,000-real (about $150,000) bribe from the boss of a meatpacking company implicated in a corruption scandal.

Janot is also investigating the president on two other counts: obstruction of justice and criminal organisation. Much of the evidence has come through plea deals.

Temer denies all wrongdoing. "I say without fear of being wrong that the accusation is fiction," said Temer last week.

Lima is the second ex-cabinet official from Temer's administration to be arrested in less than a month.

Two weeks ago former tourism minister Henrique Eduardo Alves was jailed in connection with an alleged corruption scheme involving a football stadium built for the 2014 World Cup.

Also on Monday, the presidency's ethics committee opened investigations into Temer's communications and trade ministers, both of whom are accused of corruption and deny any wrongdoing.

The committee does not have the power to remove them from office, but the probes are further embarrassments for Temer.

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Meanwhile, Temer will attend this weekend's G20 meeting in Germany, reversing his previous decision to skip the meeting and stay in Brazil his office announced on Monday.

Temer's leading advisors convinced him that he could not be absent from the meeting on July 7 and 8 in Hamburg, the O Globo news portal reported.

Temer had previously announced he would not attend the meeting of leaders from the world's largest industrialised and emerging economies, with media speculating he would use the time to try and save his job.