President Donald Trump said Monday he “never worked for Russia,” after reports that the FBI grew so concerned by his actions toward Moscow that they quietly began a counterintelligence investigation into whether he was working on its behalf.

Trump, speaking to reporters as he left the White House for an agriculture event in New Orleans, said the investigation was a “hoax.”

The probe, which followed the firing of James Comey as FBI director, focused on whether Trump’s actions ever posed a threat to national security and whether the dismissal constituted obstruction of justice, the New York Times reported. Special Counsel Robert Mueller took over the investigation as part of his own examination of Russian interference in the 2016 election Trump won.

“It’s so ridiculous, these people make it up,” Trump told Fox News host Jeanine Pirro on Saturday. He added that he’d been tougher on Russia than recent U.S. leaders.

Democrats including Senator Dick Durbin of Illinois have said the reports highlighted the need for Mueller to finish his investigation without interference. Durbin said on ABC’s "This Week" that Trump’s pick for attorney general William Barr needs to give lawmakers "iron-clad" assurances he won’t interfere in the matter.

On Saturday, a Washington Post story said Trump went to great lengths to hide details of his discussions with Russian President Vladimir Putin.

According to a separate report in the Wall Street Journal on Sunday, Trump didn’t have official note takers present during a more than two-hour meeting with Putin in Hamburg, Germany, in July 2017. Many top administration officials never were briefed on the discussion, the Journal said, citing several officials familiar with the matter.