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WASHINGTON, DC - JUNE 08: Former FBI Director James Comey leaves a closed session with the Senate Intelligence Committee in the Hart Senate Office Building on Capitol Hill June 8, 2017 in Washington, DC. Comey said that President Donald Trump pressured him to drop the FBI's investigation into former National Security Advisor Michael Flynn and demanded Comey's loyalty during the one-on-one meetings he had with president. (Photo by Drew Angerer/Getty Images)
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WASHINGTON, DC - JANUARY 22: U.S. President Donald Trump (L) shakes hands with James Comey, director of the Federal Bureau of Investigation (FBI), during an Inaugural Law Enforcement Officers and First Responders Reception in the Blue Room of the White House on January 22, 2017 in Washington, DC. Trump today mocked protesters who gathered for large demonstrations across the U.S. and the world on Saturday to signal discontent with his leadership, but later offered a more conciliatory tone, saying he recognized such marches as a "hallmark of our democracy." (Photo by Andrew Harrer-Pool/Getty Images)
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(CNN) —  

Former FBI Director James Comey pushed back on President Donald Trump’s spying claims on Wednesday, warning that attacking the FBI “will do lasting damage to our country.”

In a tweet that did not address the President by name, the former FBI director wrote, “Facts matter. The FBI’s use of Confidential Human Sources (the actual term) is tightly regulated and essential to protecting the country. Attacks on the FBI and lying about its work will do lasting damage to our country. How will Republicans explain this to their grandchildren?”

In a second tweet on Wednesday, Comey called on the American public to “seek truth.”

The comments from Comey, who was abruptly fired by the President last year, come after Trump questioned whether the FBI placed “spies” in his campaign.

Multiple outlets reported last week that a confidential source working for the FBI spoke with several Trump campaign aides. US officials have told CNN, however, that a confidential intelligence source was not planted inside the campaign to provide information.

The Justice Department has asked its inspector general to determine whether there was any wrongdoing in the FBI’s handling of its Russian interference counterintelligence investigation.

CNN’s Shimon Prokupecz, Jim Sciutto, Laura Jarrett and Manu Raju contributed to this report