The House committee investigating the January 6 insurrection at the US Capitol is reportedly looking at a “possible cover-up” of White House records focusing on Donald Trump’s phone logs from that fateful day, which bear an unexplained gap of seven hours and 37 minutes covering the period when the violence was unfolding.

Documents obtained by the Washington Post and CBS News put flesh on the bones of one of the great mysteries of January 6: why White House phone logs contain holes in the record despite evidence the then president busily made calls at the height of the insurrection.

The documents reveal that Trump’s diary shows an entry at 11.17am when he “talked on a phone call to an unidentified person”. The next entry is not until 6.54pm – 457 minutes later – when Trump asked the White House switchboard to place a call to his communications chief, Dan Scavino.

Between those times Trump addressed a rally on the Ellipse, exhorting supporters to “fight like hell”; hundreds of Trump followers overran police barricades and stormed the Capitol building; and Mike Pence, the vice-president, who had been overseeing the certification of Joe Biden’s victory in the presidential election, was forced to go into hiding.

A bipartisan Senate report connected seven deaths to the attack. More than 100 law enforcement officers were injured.

In an echo of history, the investigation by the January 6 committee of a possible cover-up was revealed by Bob Woodward of the Washington Post, who made his name, with Carl Bernstein, by breaking the story of Watergate and bringing down a president, Richard Nixon. Woodward’s journalistic partner on this occasion was Robert Costa, his co-author of Peril, a book on the end of the Trump presidency which was released last year.

The pair reported that the long gap between call logs was of “intense interest” to elements of the January 6 committee. They quoted an unnamed member of the panel who said they were investigating a “possible cover-up”.

The January 6 committee consists of nine members, seven Democrats and two Republicans, Liz Cheney of Wyoming and Adam Kinzinger of Illinois, participating in defiance of party leadership.

According to Woodward and Costa, the committee is looking at possible ways in which Trump skirted normal accountability governing telephone calls for a sitting president. One theory is that he might have used disposable or “burner phones”.

In a statement, Trump dismissed such speculation.

“I have no idea what a burner phone is, to the best of my knowledge I have never even heard the term,” he said.

The disclosure of evidence around the events of January 6 has been a bone of contention between Trump and the House committee. Last month the National Archives disclosed it had found boxes of classified documents the former president had improperly taken from the White House.

The phone logs containing the six-hour interlude were only handed over to the committee earlier this year after the US supreme court rejected a call by Trump to block the transfer of the documents.

The apparent parallels between Trump’s missing phone logs and Nixon’s Watergate cover-up – both situations enhanced by the presence of Woodward’s reporting – was too enticing for commentators to ignore.

Bill Kristol, editor-at-large of the anti-Trump conservative website The Bulwark, compared the two presidents’ remarks, writing: “‘I have never obstructed justice … I am not a crook.’ – Richard M Nixon, Nov 17, 1973. ‘I have no idea what a burner phone is …” – Donald J Trump, March 29 2022.’ ”

Several people noted the disparity between the infamous 18-and-a-half minutes that were missing in White House tapes of conversations between Nixon and his chief of staff, HR Haldeman, and the vastly longer gap of more than seven hours in Trump’s phone logs.

The missing Nixon tapes were from 20 June 1972, three days after the Watergate break-in.

The constitutional law scholar Laurence Tribe tweeted that Trump’s gap “makes the infamous 18-minute gap in Nixon’s tapes look like nothing in comparison”.

Pressure on Trump over his actions on January 6 comes at an intense moment for him. Earlier this month, the committee laid out a case for the former president having violated several federal laws in his attempt to overturn the 2020 election results and stay in power.

This week, a federal judge stated that Trump appeared to have committed multiple felonies in his pursuit of the “big lie” that the election was stolen. The judge, David Carter, ordered John Eastman, the conservative lawyer who advised Trump on how to delay certification of Biden’s victory, to hand over hundreds of emails to the January 6 committee.