A 10in-thick binder containing nearly 3,000 pages of highly classified material related to the investigation of Russian election interference as well as links between Moscow and Donald Trump went missing in the final days of his presidency, CNN and the New York Times reported. CNN said the disappearance raised alarms in the American intelligence community because “some of the most closely guarded national security secrets from the US and its allies could be exposed”. The Times said national security officials were “vexed” by the disappearance of the “Crossfire Hurricane binder”, which was “the name given to the investigation by the FBI”. The issue was so concerning, the Times added, the Senate intelligence committee was briefed. Now the frontrunner for the Republican presidential nomination, Trump faces 91 criminal charges arising from his conduct since entering politics in 2015. Forty charges, brought by the special counsel Jack Smith, concern the retention of classified information after leaving office. In August 2022, FBI agents searched Trump’s Florida home. They did not find material related to the Crossfire Hurricane investigation, the Times said. The investigation of Russian interference in the 2016 election won by Trump ended in April 2019. At that time, a report by the special counsel Robert Mueller laid out evidence of Russian interference and links between Trump and Moscow and occasions on which Trump may have tried to obstruct justice. But Mueller did not establish collusion between Trump and Russia. Aided by his second attorney general, William Barr, Trump claimed exoneration. On Friday, reports about the missing binder – which the Times said ran to 2,700 pages – brought the Russia investigation back to the headlines. According to the Times, the binder contained “a hodgepodge of materials related to the origins and early stages of the Russia investigation that were collected by Trump administration officials”. That “hodgepodge”, the paper said, “included copies of botched FBI applications for national security surveillance warrants to wiretap a former Trump campaign adviser as well as text messages between two FBI officials … expressing animus toward Mr Trump”. The paper said the “substance” of the material was not particularly sensitive and was posted online, with redactions, by the FBI. Official concerns centered on what the binder could reveal about sources and methods, the Times said, while noting that the online version runs to 585 pages – more than 2,000 fewer than the missing binder. “Among other murky details,” the paper said, “it is not known how many copies were made at the White House or how the government knows one set is missing.” CNN said “multiple copies” of the binder were created in the last hours of the Trump administration, “with plans to distribute them … to Republicans in Congress and rightwing journalists”. Trumped ordered declassification but that has not happened in full. Reportedly “deeply focused” on the binder, Trump offered to let the author of a book about him have a look inside. “I would let you look at them if you wanted,” Trump said in April 2021, according to the Times. “It’s a treasure trove … it would be a sort of cool book for you to look at.” Maggie Haberman, one of the reporters on Friday’s piece, wrote a book about Trump which was published last year. Trump indicated that his last White House chief of staff, Mark Meadows, had the binder. A lawyer for Meadows told the Times his client “never took any copy of that binder home at any time”. Presented with the CNN report, one former Trump national security aide simply said, in a message viewed by the Guardian: “Holy cow.”