(NBC News) - President Donald Trump said he's concerned over the friendship between former FBI Director James Comey and special counsel Robert Mueller, who was selected to replace Comey to investigate the Russian meddling in the 2016 election.

In an interview that aired Friday on "Fox and Friends," Trump said Mueller is "very, very good friends with Comey, which is very bothersome."

Trump had fired the FBI chief in May, in part, for his handling of the inquiry into the Trump campaign's possible ties with Moscow. U.S. intelligence agencies say Russia sought to undermine the presidential election in favor of the Republican nominee. A week after Comey was ousted, Mueller was appointed to oversee the probe.

When asked if Mueller should recuse himself because of his friendship with Comey, Trump responded: "We're going to have to see." The men worked closely together during the George W. Bush administration.

Last week, it was revealed that Mueller — who led the FBI from 2001 to 2013 before Comey was tapped — had requested interviews with top intelligence officials about their conversations with Trump in an effort to investigate possible obstruction of justice.

Rumors also swirled around Washington that Trump was considering firing Mueller.

Trump denied there has been any attempt to obstruct the investigation.

"There has been no collusion — there has been leaking by Comey," he told "Fox and Friends." "But there's been no collusion, no obstruction, and virtually everyone agrees to that."

Trump also reiterated a tweet he wrote Thursday that he never actually had tapes of his conversations with Comey before he was fired.

"Well I didn't tape him," the president said. "You never know what's happening when you see that the Obama administration, and perhaps longer than that, was doing all of this unmasking and surveillance."

"You've been hearing the word unmasking — a word you probably never heard before, so you never know what's out there, but I didn't tape and I don't have any tape," he added.

"But when he found out that there may be tapes out there, whether it be governmental tapes or anything else, I think his story may have changed ... my story didn't change, my story was never a fake story."

Trump first tweeted in May following Comey's removal that the veteran lawman had "better hope that there are no 'tapes'" of their conversations.

No tapes were ever uncovered, but Comey later revealed during a Senate Intelligence Committee hearing that he orchestrated the release of a memo that detailed conversations between him and the president.