WASHINGTON (Reuters) - Former top FBI official Andrew McCabe said he began an obstruction of justice and counterintelligence investigation involving U.S. President Donald Trump and his ties to Russia after Trump fired bureau Director James Comey in May 2017, CBS News reported on Thursday.

McCabe, who became acting director after Comey’s firing, said he was disturbed by his conversation with Trump following Comey’s dismissal and got the investigations started the following day, according to excerpts from an interview with “60 Minutes” to be broadcast on Sunday.

“I was speaking to the man who had just run for the presidency and won the election for the presidency and who might have done so with the aid of the government of Russia, our most formidable adversary on the world stage. And that was something that troubled me greatly,” said McCabe.

In the first public confirmation of the investigation by an official who was involved, McCabe described events that occurred in the eight days between Comey’s firing and the appointment of Special Counsel Robert Mueller to take over the investigations of Russian interference in the 2016 U.S. election, CBS said.

“I was very concerned that I was able to put the Russia case on absolutely solid ground in an indelible fashion that were I removed quickly and reassigned or fired that the case could not be closed or vanish in the night without a trace,” said McCabe, who is promoting a book to be released next week, “The Threat: How the FBI Protects America in the Age of Terror and Trump.”

McCabe confirmed a New York Times report in September that there were meetings at the Justice Department about whether the vice president and Cabinet members could be gathered to remove Trump under the Constitution’s 25th Amendment, which outlines how a sitting president can be removed.

McCabe also confirmed the newspaper’s account that Deputy Attorney General Rod Rosenstein considered wearing a wire in meetings with Trump, CBS reported.

Rosenstein denied the report at the time and a Justice Department spokeswoman said on Thursday that Rosenstein again rejects McCabe’s account as “inaccurate and factually incorrect.”

Mueller’s office is examining possible coordination between Moscow and the Trump campaign. Moscow has denied interfering and Trump says there was no collusion with his campaign.

Trump, who has frequently criticized Comey, McCabe and the Russia inquiry, on Thursday attacked McCabe on Twitter as a leaker and a “disgrace to the FBI.”

In June 2017, Comey told a Senate committee he believed Trump had directed him to drop a probe into the Republican president’s former national security adviser, Michael Flynn, as part of the broader Russia investigation.

McCabe himself was fired in March 2018 by then-U.S. Attorney General Jeff Sessions, who cited an internal Federal Bureau of Investigation watchdog report that found McCabe leaked information to reporters and misled investigators about his actions. McCabe said he was targeted over the Russia probe.

The Republican chairman of the Senate Judiciary Committee, Lindsey Graham, called on McCabe to appear before the panel to “answer questions about what appears to be, now more than ever, bias against President Trump.”