© Reuters/Tom Brenner
US President Donald Trump
President Donald Trump has slated the FBI's surveillance operation against him, calling it a "disgrace" and "an embarrassment to our country," after a Justice Department report found "mistakes" in the agency's conduct.

"This was an attempted overthrow and a lot of people were in on it, and they got caught," Trump told reporters at the White House on Monday, hours after the Justice Department's Inspector General released a report on the origins of the FBI's 2016 counterintelligence probe against the Trump campaign.

"It's a's incredible, far worse than I would have ever thought possible. It's an embarrassment to our country," he continued, "it's dishonest. It's everything a lot of people thought it would be, except far worse."

Despite Trump's strong words, the report's authors say they only found that the FBI had made "mistakes" in its operation, and did not act with political bias.

Trump and his supporters may disagree. The report noted that the now-discredited 'Steele Dossier' played a "central and essential role" in backing up the FBI's warrant application to surveil Trump campaign associate Carter Page. It also did not find a series of anti-Trump messages between former agent Peter Strzok and agency lawyer Lisa Page to be evidence of bias.

The FBI did not tell the Justice Department that Steele's information had been false, and the agency continued to spy on Page even after Trump's election.

Attorney General William Barr said that the report showed that the FBI had "launched an intrusive investigation of a US presidential campaign on the thinnest of suspicions."

Federal prosecutor John Durham, who has been tasked by Barr to run his own investigation into the FBI's conduct, said on Monday that he does "not agree" with some of the report's conclusions, and hinted that his own report will be more damning for the FBI.