, Brazil’s interim president, has rejected allegations he solicited bribes during the election campaign of a political ally for São Paulo mayor in 2012.

The claims against Mr Temer were contained in a plea bargain released by the former head of a state-owned oil company, Sérgio Machado, released to the public by the Supreme Court on Wednesday, Brazilian media reported.

In a statement, office denied the claims, saying: “[Mr Temer] never permitted the collection of funds outside of the dictates of the law, whether for himself, for the party, or even less for other candidates who he occasionally supported in elections”.

The accusations that Mr Temer sought bribes are the latest challenge to his fledgling government as he seeks to cement his rule amid an impeachment process against Brazil’s elected president Dilma Rousseff.

A leader of the centrist PMDB party, Mr Temer power after the start of the impeachment procedure against the leftist Ms Rousseff in mid-May for allegedly manipulating the budget.

Mr Machado’s accusations are the most direct yet against Mr Temer in a wider investigation into , the state-owned oil company that prosecutors allege was used by politicians as a source of illegal campaign funding for elections.

“Throughout his public life, interim president Michel Temer has always respected the legal limits for seeking resources for election campaigns,” the statement from his office said.

Under the allegations, which were reported in Brazilian media citing the legal documents released from the Supreme Court, Mr Temer directly requested R$1.5m from Mr Machado, then head of oil group Transpetro, to support the 2012 campaign for São Paulo mayor of party ally Gabriel Chalita.

The money was allegedly paid in the form of a legal donation from a construction company, which had contracts with Transpetro.

Mr Machado allegedly made clear to Mr Temer that while the money would be transferred in the form of a legal donation, it would come from illegal sources.

However, analysts at Eurasia Group, a risk consultancy, said the allegations were sufficiently vague as to avoid posing a serious threat to Mr Temer.

Seeking a campaign donation was not necessarily illegal and it seemed Mr Machado did not have proof this money had come from bribes or other illegal sources, Eurasia Group said.

“We remain sceptical that his plea bargain proves very damaging to Temer,” Eurasia Group said.

The allegations against Mr Temer were among a wave of similar accusations against all sides of the political spectrum made by Mr Machado in his plea bargain, Brazilian media reported, with opposition parties such as the centrist PSDB also coming under attack.

The PSDB said the allegations were made by someone “desperate to free himself of responsibility for the crimes he committed”.

The allegations also provoked a rebuttal from the head of the senate, Renan Calheiros, one of the most senior politicians named by Mr Machado, who said all of his campaign donations had been legal.