President Donald Trump called James Comey a "leaker" on Friday, the day after his former FBI director accused him in a U.S. Senate hearing of lying and trying to quash an investigation into former national security adviser Michael Flynn.

"Despite so many false statements and lies, total and complete vindication ... and WOW, Comey is a leaker!" Trump tweeted in his first comments since Comey appeared before the Senate Intelligence Committee on Thursday.

Trump broke his silence on Comey's testimony with a single tweet that echoed the points made by his private lawyer after the hearing: Trump himself was not under investigation and Comey gave an account of his conversation with him to a lawyer friend who shared it with a news outlet.

The Republican president stopped short of saying that Comey lied under oath at the hearing, which occurred a month after Trump fired him on May 9.

In his public testimony, Comey did not disclose any links between Trump advisers and alleged Russian attempts to meddle in the 2016 U.S. presidential election, an issue that has distracted from White House policy goals such as overhauling the U.S. healthcare system and cutting taxes.

Russia has denied such interference. The White House has denied collusion with Moscow.

In the highly anticipated hearing, Comey delivered a scathing indictment of his former boss, accusing him of trying to block the Flynn probe and saying the White House defamed him and the Federal Bureau of Investigation in trying to explain his dismissal.

He told the Senate panel he took meticulous notes of each meeting or conversation he had with Trump because "I was honestly concerned that he might lie about the nature of our meeting, and so I thought it really important to document."

Comey said he shared an unclassified memo of their conversation about Flynn because he hoped it would lead to the appointment of a special counsel.

Robert Mueller, a former FBI director, was appointed as special counsel the week after Comey's firing, which set off a political firestorm and raised suspicions among Democrats and others that the White House was trying to blunt the FBI probe.

Comey would not say whether he thought Trump tried to obstruct justice, leaving that determination to Mueller.

"I don't think it's for me to say whether the conversation I had with the president was an effort to obstruct," Comey testified. "I took it as a very disturbing thing, very concerning."

Senator Tim Kaine, the 2016 Democratic vice presidential candidate, said on Friday that Comey's testimony provided a wealth of information for both the congressional and special counsel investigations.

"What we're talking about is a sitting president of the United States and whether the administration took an action to fire the FBI director in a historic way because of a desire to take the pressure off the Russia investigation," he told CNN.