WASHINGTON, June 15 (Xinhua) -- U.S. President Donald Trump launched fierce attacks Friday on former FBI Director James Comey, a day after the release of a watchdog report that concludes there were errors, not political bias in the agency's handling of its investigation of Hillary Clinton's use of private email server.

In a flurry of tweets Friday morning, Trump said that the report, conducted by the U.S. Department of Justice's inspector general, is a "total disaster" for Comey and the FBI, claiming that he "did a great service to the people" in firing the agency's former chief.

According to the highly-anticipated report, Comey was insubordinate but not driven by political bias when making some key decisions as to the probe of Clinton's email use while she was secretary of state, during the period of the 2016 presidential campaign, which have drawn criticism from Republicans and Democrats alike.

The 500-page report also concluded that the Clinton email probe was not tainted by political bias, even though it was critical of two FBI staff members who exchanged highly charged political messages over Trump, finding that their texts created the appearance of bias and cast cloud over the FBI.

During an interview with Fox News Channel at the White House Friday morning, Trump said "the end result was wrong" and there was "total bias." Later, he told other reporters that "Comey was the ring leader of this whole, you know, den of thieves. It was a den of thieves."

Responding to the report Thursday, Comey tweeted that he respects the Inspector General's office and that their "conclusions are reasonable," even though he disagreed with some of them. He said that "people of good faith" can see the "unprecedented situation differently."

Comey was fired by President Donald Trump in May 2017. He has repeatedly criticized Comey for his handling of the Clinton probe and also targeted top officials of the FBI and the DOJ for what he called political bias against him.

Trump's defenders, including his lawyer and some Republicans, have seized on the report to justify Comey's ouster, while Democrats were concerned that the report would be used to undercut the ongoing Russia probe led by special counsel Robert Mueller, whose appointment followed Comey' s departure.

Mueller is looking into the alleged Russian interference in the 2016 U.S. presidential election and any potential collusion between the Trump campaign and Moscow, among other matters that may arise from the investigation.

Trump, who has repeatedly called the Russia probe "hoax" or "witch hunt," has ratcheted up pressure on it in the past months. Russia has denied interference in the election campaign.

Trump's personal lawyer, Rudy Giuliani, said Friday that the report casts doubt on whether the president would ever agree to an interview with Mueller's team.

Trump himself said he had "reservations" about a sit-down with the investigators.

FBI Director Christopher Wray defended his agency on Thursday, saying that the report only addresses a specific set of facts and the actions of a handful of officials and that "nothing" in it "impugns" the integrity of the FBI workforce as a whole.