The report by Justice Department Inspector General Michael Horowitz concluded there was no evidence to suggest that undercover FBI agents participated in the attack on the US Capitol.
The report also found the FBI did not authorise any of its informants to enter the building or engage in violence.
The FBI has long denied having any involvement by its own staff or its informants in the riots at the Capitol, though conspiracy theories about its role in the attack have persisted.
One such false claim pertained to James Ray Epps, an Arizona man who entered the Capitol that day. Epps, who was charged last year with a misdemeanour for entering a restricted building or grounds, was falsely accused by Trump's supporters and by former Fox News host Tucker Carlson of being an undercover government informant.Â
Horowitz's report comes a little more than a month before Trump will be sworn in for his second term as president. He has pledged to grant clemency to many of the people who stormed the Capitol as soon as his first day in office.
The report found that the FBI could have done more ahead of the January 6 attack by canvassing its field offices for intelligence from informants to prepare for what was to come.
Twenty-six FBI confidential informants were in Washington, D.C., on the day of the attack, the report said.
Three of them were tasked with reporting on domestic terrorism case subjects. One of those three entered the Capitol that day, while two others entered a restricted area around the Capitol.
The other 23 informants who were in Washington to attend protests did so on their own initiative and were not asked by the bureau to attend the events, the report said.
Several of the informants cited in the report on Thursday were tasked with providing the FBI with information related to far-right groups including the Oath Keepers and the Proud Boys. Leaders for both the Oath Keepers and Proud Boys were later prosecuted for their involvement in the Capitol attack, with juries convicting Oath Keepers founder Stewart Rhodes and Proud Boys former chairman Enrique Tarrio of seditious conspiracy and other crimes.
In its response to the report, the FBI said it will accept the watchdog's recommendations for how to improve its processes to prepare for future events that could pose domestic security issues.
