President Trump accused Biden of being a “big unmasker” after the vice president claimed day earlier he didn't know much about the investigation started by Obama officials into Michael Flynn.

“I was watched Biden yesterday being interviewed on 'Good Morning America' by one of your colleagues George Stephanopoulos, he said he knew nothing about anything,” Trump said at a meeting with governors of Colorado and North Dakota. “Nothing at all. Then it gets released today he was a big unmasker. How do you know nothing if you’re one of the unmaskers?”

"Unmasking is a massive thing," the president added. "Who can believe a thing like this?"

LIST OF OFFICIALS WHO SOUGHT TO 'UNMASK' FLYNN RELEASED: BIDEN, COMEY, OBAMA CHIEF OF STAFF AMONG THEM 

It was revealed Wednesday that Biden was purportedly among a number of top Obama officials who sought to “unmask” the identity of former national security adviser Michael Flynn from surveillance transcripts of Russian Ambassador Sergey Kislyak’s phone conversation during the presidential transitional period.

Biden, during an interview with ABC’s “Good Morning America,” initially said he knew nothing about the investigation into Flynn, before later correcting himself.

“I know nothing about those moves to investigate Michael Flynn,” Biden initially said, calling the topic a “diversion” from the coronavirus pandemic.

Stephanopoulos, though, pressed Biden again, questioning whether he attended an Oval Office meeting on Jan. 5, 2017—during the presidential transition period—where Flynn apparently was discussed.

“No, I thought you asked me whether or not I had anything to do with him being prosecuted,” Biden said. “I’m sorry.”

“I was aware that there was—that they asked for an investigation, but that’s all I know about it, and I don’t think anything else ...”

In a statement on Wednesday, Andrew Bates, Biden's Director of Rapid Response, downplayed the latest Flynn revelations.

"These documents have absolutely nothing to do with any FBI investigation and they confirm that all normal procedures were followed -- any suggestion otherwise is a flat out lie,” Bates said. “What's more, it's telling that these documents were selectively leaked by Republicans abusing their congressional powers to act as arms of the Trump campaign after having them provided by a partisan official installed for this very purpose."

He added: "The only people with questions to answer are Grenell, Sen. Grassley, and Sen. Johnson for their gross politicization of the intelligence process."

Biden’s comments come as questions about what he and Obama knew about the origins of the investigation into whether the Trump campaign colluded with Russia in the 2016 presidential election were revived last week, as newly released documents revealed additional details about that Jan. 5, 2017, Oval Office meeting.

An exhibit in the Justice Department’s motion to dismiss the case against Flynn last week detailed a special counsel interview of former Deputy Attorney General Sally Yates. The interview indicated Obama was aware of Flynn’s intercepted December 2016 phone calls with then-Russian Ambassador Sergey Kislyak during the presidential transition period.

The document noted Yates learned about the calls during that meeting with Obama, Rice, then-FBI Director James Comey, then-CIA Director John Brennan, and then-Director of National Intelligence James Clapper.

WHO ARE THE OBAMA-ERA OFFICIALS WHO SOUGHT TO 'UNMASK' MICHAEL FLYNN? 

After the briefing, Obama asked Yates and Comey to "stay behind," and said he had "learned of the information about Flynn" and his conversation with Russia's ambassador about sanctions. Obama "specified that he did not want any additional information on the matter, but was seeking information on whether the White House should be treating Flynn any differently, given the information.”

The Oval Office meeting aligns with an email that Rice on Jan. 20, 2017, the day President Trump was sworn into office — sent herself documenting Obama’s guidance, evidently in the same meeting, about how law enforcement should investigate Russian interference in the 2016 presidential race.

The email was partially unclassified and appeared to detail that same Jan. 5, 2017, meeting, also said to include Biden. The message was first flagged in 2018 by Sens. Chuck Grassley, R-Iowa, the former Senate Judiciary Committee chairman, and Lindsey Graham, R-S.C., who now sits as chairman of the panel.

This eventually led to Flynn being interviewed, amid supposed concern he had violated the obscure and never-successfully-enforced Logan Act, and later pleading guilty to lying to investigators about his Kislyak talks.

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The filing to dismiss the Flynn case came after the DOJ determined that the bureau's 2017 Flynn interview -- which formed the basis for his guilty plea of lying to investigators -- was "conducted without any legitimate investigative basis.”

Fox News' Brooke Singman and Madeleine Rivera contributed to this report.