(Adds comments from parties and politicians targeted in the investigation and from the Prosecutor General Rodrigo Janot)
By Marcela Ayres and Maria Carolina Marcello
BRASILIA, March 14 (Reuters) - Brazil's top public prosecutor asked the Supreme Court to open 83 new investigations into senior politicians on Tuesday, reportedly including five ministers and leading lawmakers, in a dramatic escalation of a graft probe threatening the government.
Prosecutor General Rodrigo Janot also requested that the Court send 211 other requests to lower courts based on much-anticipated testimony by dozens of executives of engineering group Odebrecht SA in Brazil's biggest-ever corruption scandal.
Brazilian newspapers reported that Janot called for an investigation of five members of President Michel Temer's cabinet, along with his most senior allies in Congress, raising concerns about the stability of his administration and the fate of fiscal reforms cheered by investors.
Temer said last month that he would suspend any cabinet member who is placed under investigation and would dismiss them only if they are indicted for corruption.
Under Brazilian law, cabinet ministers, federal senators and lower house lawmakers can be tried only in the Supreme Court, where cases often take years to come to trial.
Janot could not disclose the names of the politicians and others covered by his request as the Odebrecht testimony and related investigations are still under seal. He asked Supreme Court Justice Edson Fachin to lift the judicial secrecy on the case for the sake of transparency and the public interest.
In a letter to explain the operation, Janot said his actions on Tuesday will remind Brazilians "of the sad reality of a democracy under attack by the corruption and the abuse of political and economical powers."
President Temer himself has not been directly implicated in illicit party funding and has denied any wrongdoing in the sprawling three-year corruption scandal centered on overpriced contacts at state-run oil company Petroleo Brasileiro SA .
Dozens of politicians reportedly named for taking kickbacks in the testimony by Odebrecht executives included senators in Temer's Brazilian Democratic Movement Party (PDMB) and the allied Brazilian Social Democracy Party (PSDB), which led the impeachment of leftist Dilma Rousseff last year.
Janot called for lower courts to investigate Rousseff and her predecessor and political mentor Luiz Inacio Lula da Silva, according to newspapers O Globo, O Estado de S.Paulo and Folha de S.Paulo. Both former presidents have repeatedly denied any involvement or knowledge of alleged corruption.
The new investigations will be a test for Temer as he strives to pull Latin America's largest nation out of its worst recession in more than a century.
Temer succeeded Rousseff in May, vowing to eliminate corruption and restore fiscal discipline, but he has already lost several ministers to bribery allegations.
His chief of staff, Eliseu Padilha, a key organizer of political support in Congress for a crucial reform of Brazil's costly pension system, is on thin ice after an Odebrecht executive was reported to have said he asked for a cash donation for Temer's 2014 campaign.
Newspapers Globo, Folha and Estado reported that Padilha and four other members of Temer's cabinet were on Janot's list: Foreign Minister Aloysio Nunes, Science Minister Gilberto Kassab, Cities Minister Bruno Araújo and Wellington Moreira Franco, the head of Temer's high-profile infrastructure privatization program.
Janot also called for the investigation of key Temer allies in Congress, according to the newspapers, including lower House Speaker Rodrigo Maia and the three most senior PMDB senators: Senate President Eunicio Oliveira and senators Romero Juca and Renan Calheiros.
Foreign Minister Aloysio Nunes said he required access to Janot's accusations and will only comment when he is aware of the content. Cities Minister Araújo said he has asked for campaign donations from Odebrecht in the past, but did so in accordance with the law.
Senator Romero Jucá said he is available to collaborate with investigations and believes facts will be clarified.
Reuters was not able to confirm the media reports. The other politicians cited were not immediately available for comment, but they all have consistently denied wrongdoings.
The PMDB released a statement on Tuesday expressing support for the investigations and calling for "the clarification of the facts of the matter."
PSDB said it has always defended the Car Wash investigation, believing that it is the only way to separate guilty from innocent.
Finance Minister Henrique Meirelles said news of the investigation should not hurt progress on the government's pension reform.
Janot first opened investigations of seated politicians implicated in the kickback scandal in March 2015, but only five have been indicted and none convicted.
The new round of investigations fueled by the Odebrecht testimony follows 10 months of negotiations with the family-owned firm, Latin America's largest engineering group.
In December, Odebrecht signed a leniency accord with prosecutors, agreeing to pay 6.7 billion reais ($1.9 billion), admit guilt and offer details of bribes it paid.
Seventy-seven of its executives, including family patriarch and Chairman Emilio Odebrecht and his jailed son and former Chief Executive Marcelo Odebrecht, made some 950 statements to a team of 116 prosecutors across the country, Janot's office said. ($1 = 3.17 reais)
Reporting by Marcela Ayres and Maria Carolina Marcello; Writing by Brad Haynes, Anthony Boadle and Marcelo Teixeira; Editing by Daniel Flynn, Dan Grebler and Lisa Shumaker