RIO DE JANEIRO - Brazilian President Dilma Rousseff on Wednesday insisted that the accusations against her are "untruthful," after the prosecutor general requested that Rousseff be investigated for obstruction of justice.

Brazil's President Dilma Rousseff reacts during a launch ceremony of Agricultural and Livestock Plan for 2016/2017, at the Planalto Palace in Brasilia, Brazil May 4, 2016.  [Photo/Agencies]

The investigation, if allowed by the Supreme Court, will only find out that those who accused her have lied, said the president.

Senator Delcidio do Amaral has testified and accused Rousseff of trying to interfere in the Carwash Operation, the three-year-long Federal Police probe aimed at uncovering a major corruption scheme at Petrobras and its developments.

Amaral's testimony was recently leaked to the press but without accompanying evidence.

"Senator Delcidio's words are absolutely fallacious and untruthful," Rousseff said at a ceremony of the government's Agricultural Plan.

General Prosecutor Rodrigo Janot on Tuesday requested an investigation be started on the testimony of Amaral. It is the first time that Rousseff has been officially accused since the scandal broke out.

"I am aware of Senator Delcidio's list and I think his credibility is rather precarious. I believe it is necessary to investigate where his statements came from," she said.

Rousseff is going through an impeachment process and her case is being analyzed by a Senate commission.

Should the Senate, which is due to vote on May 11, decide to begin an impeachment trial, Rousseff will have to be out of office for 180 days for the trial to proceed, with Vice President Michel Temer taking over as acting president.

If Rousseff is finally impeached with a two-thirds majority of the Senate, Temer will complete her mandate through Jan. 1, 2019.