"The FBI had this material for a long time," he told MSNBC. "But he, Comey, who's a Republican, refused to divulge this information about Russia interfering with the presidential election."
Comey "should be investigated by the Senate" and "other agencies of the government, including the security agencies because if there were ever a matter of security, it's this," Reid said.
However, he added that he does not believe Attorney General Loretta Lynch should try to fire the FBI chief.
"There's not enough time to do that, that would be a gesture in futility," he said.
Comey "let the country down for partisan purposes," Reid said, calling him "the new J. Edgar Hoover," a reference to the powerful long-time FBI director (1935-1972) who carried out domestic espionage against political dissidents and collected secret files of dirty secrets about political leaders.
Republicans on Saturday rejected news reports about a secret CIA assessment finding that Russia sought to tip the US election in Trump's favor.
The New York Times reported that US intelligence agencies had "high confidence" that Russian hackers infiltrated the Republican National Committee's computer systems as well as Democratic Party's, but released information taken only from Democratic computers.
Reid's successor as the top Senate Democrat, Chuck Schumer, also called for a congressional investigation into the matter on Saturday.