Notebooks from Boris Johnson’s time as prime minister are being held by the British government after a review by the security services found they contained highly sensitive material.
Officials said the passages included in a collection of 25 notebooks must only be seen by people with the highest level of security clearance, according to reports.
And if they are returned to Mr Johnson, they must be “appropriately stored”, they said.
Concerns have also been raised about some of the former Conservative leader’s WhatsApp messages, The Times reported.
Baroness Hallet, the chairwoman of the Covid inquiry, wants access to unredacted copies of Mr Johnson’s notebooks and messages, but the Cabinet Office has so far refused the request, saying it is only willing to provide redacted copies.
It told the inquiry some of the material “may involve issues of national security”.
A person close to Mr Johnson told the newspaper there was no sensitive security material in the notebooks.
But, according to the report, the review by the security services identified “multiple” instances of sensitive information.
On Monday, which is Mr Johnson’s 59th birthday, MPs will vote on the privileges committee report, which found he misled the House of Commons five times in his denial of Covid-19 rules being broken in Downing Street.
The government has given Conservative MPs permission to abstain by staying away. It is not known how Prime Minister Rishi Sunak himself will vote.
“Politically it’s in his interests for it to be a firm verdict on Boris Johnson,” said Hannah White, director of the Institute for Government. The balance is between upsetting Johnson supporters and “exerting his authority,” she said.
Labour will use the vote to argue Mr Sunak is weak, scared of Johnson and unwilling to protect standards in public life, a party official said.
YouGov polling this week found just 20 per cent of voters think Mr Sunak is in control of his party, and 74 per cent think the Tories are divided.
In the coming weeks, Downing Street will attempt a reset with a series of new policies and a possible reshuffle promoting younger faces, a government aide said.
Another said the government plans a surge of announcements, including on cross-channel immigration, investment zones, and moving civil servants out of London.
“The party is trying to move on but Boris is a difficult person to move on from,” Robert Hayward, a Conservative peer and elections analyst, said.
