Mexico's top electoral crimes prosecutor said Friday that he is dropping the appeal against his dismissal, which opposition lawmakers had depicted as an effort by the ruling party to blunt an investigation into possible illegal campaign financing.

Santiago Nieto said he still considered his firing by Mexico's Attorney General unjust, but he was dropping his appeal because the conditions no longer existed to "carry out the functions I was designated to do."

Mexico's government dismissed Nieto a week ago for revealing parts of an ongoing investigation into possible illegal campaign money from Brazilian construction company Odebrecht in the 2012 presidential elections. Criminal investigations are not public in Mexico.

Critics of President Enrique Pena Nieto's government called it the latest attempt by the Institutional Revolutionary Party, or PRI, to insulate itself from corruption probes.

Mexico's Senate was subsequently the scene of protests after the PRI tried to hold a secret vote Nieto's dismissal.

Nieto had made the revelation in an interview published by the newspaper Reforma. In it, he said there was "information" suggesting that Odebrecht may have paid money into an account controlled by the former head of the national oil company, who at the time in 2012 played a role in Pena Nieto's campaign.

The then-electoral crimes prosecutor told Reforma that the official, Emilio Lozoya, had sent him a letter demanding his name be cleared. Lozoya has denied allegations of any misconduct involving Odebrecht, whose officials have acknowledged paying bribes for contracts in several Latin American countries.

Pena Nieto has also denied involvement in any wrongdoing related to the 2012 campaign.