John Bolton, the former national security adviser, has revealed that he heard Donald Trump use the term “burner phones” several times and that they discussed how the disposable devices were deployed by people as a way of avoiding scrutiny of their calls.

Bolton’s intervention compounds Trump’s difficulties amid a billowing controversy relating to seven hours and 37 minutes that are missing in official call logs. The gap occurs in records made for 6 January last year – the day of the violent insurrection at the US Capitol.

The Washington Post and CBS News disclosed on Tuesday that the House committee investigating the insurrection is looking into a “possible cover-up” of the White House records. Documents originally held by the National Archives and turned over to the committee earlier this year showed a gap in Trump’s phone calls spanning precisely the period when hundreds of his supporters stormed the Capitol building.

The news outlets, which obtained 11 pages of records including Trump’s official daily diary and a call log for the White House switchboard, reported that the House panel has begun an investigation into whether Trump used disposable “burner phones” to sidestep scrutiny.

In a statement to the Post/CBS News, Trump said: “I have no idea what a burner phone is, to the best of my knowledge I have never even heard the term.”

Not true, according to Bolton. In an interview with the Post/CBS News, the former national security adviser said that he recalled Trump “using the term ‘burner phones’ in several discussions and that Trump was aware of its meaning”.

Bolton added that he and Trump had spoken “about how people have used ‘burner phones’ to avoid having their calls scrutinized,” according to Robert Costa, author of the Post/CBS News revelations along with Bob Woodward.

At the heart of the January 6 committee investigation is whether Trump was directly involved in coordinating the breach of security at the Capitol on the day that Joe Biden’s victory in the 2020 presidential election was to be certified by Congress. What Trump did, and whom he talked to, as the insurrection was unfolding is central to the inquiry.

The call logs obtained by the committee show that Trump spoke to several close associates on the morning of January 6, including his lawyer Rudy Giuliani and former senior adviser Steve Bannon. His daily diary shows an entry at 11.17 am for a phone call with “an unidentified person”, but after that the records fall silent.

The next phone log is at 6.54pm when Trump asked the White House switchboard to put him through to his communications chief, Dan Scavino.

In those intervening 457 minutes Trump supporters and white supremacist groups had broken through police barricades, forcing vice-president Mike Pence, who was overseeing the certification process, into hiding. A bipartisan Senate report connected seven deaths to the attack with more than 100 law enforcement officers injured.