Rishi Sunak has been accused of attempting to cover up the actions of ministers during the pandemic as the Cabinet Office intensified its battle to withhold Boris Johnson’s WhatsApp messages from the Covid inquiry. The prime minister insisted his government has been cooperating with the investigation but is facing increasing calls from experts and MPs – with some coming from within his own party – to hand over evidence without redactions. Both Labour and the Lib Dems accused the government of a potential cover-up, while relatives of those who died in the Covid pandemic questioned what ministers have to hide. The inquiry, led by retired judge Heather Hallett, has used its sweeping powers to request unredacted notebooks, diaries and WhatApp correspondence between Johnson and 40 senior government figures. But the government is opposing the request on grounds that it wants to protect the privacy of ministers and officials, and is considering legal action to prevent disclosure. Two sources with knowledge of the inquiry’s requests said the Cabinet Office was resisting handing over the material from Johnson and his aide because they fear giving in will mean all other evidence from ministers, including Sunak himself, will have to be submitted in an unredacted form. Hallett has given the government another two days to hand over the unredacted information in relation to Johnson and one of his senior aides, Henry Cook, with the material now due by 4pm on Thursday. Refusing to comply with the inquiry’s order is a potential criminal offence. A spokesperson for Johnson said he had “no objection” to his 24 notebooks and WhatsApps being given to the inquiry, and claimed government lawyers had already been given access to them. But the Cabinet Office released a new statement on Tuesday holding firm against giving the Covid inquiry uncensored material, with the government still considering the possibility of a legal challenge. A spokesperson said: “We are firmly of the view that the inquiry does not have the power to request unambiguously irrelevant information that is beyond the scope of this investigation. This includes the WhatsApp messages of government employees which are not about work but instead are entirely personal and relate to their private lives.” However, Bloomberg reported it had seen leaked legal advice from the government’s most senior lawyer, Sir James Eadie, which suggested officials have been withholding evidence for the inquiry based on political sensitivity, rather than just personal details. It reported that the advice said: “We would be concerned by any approach which appeared to concede the principle that Cabinet Collective Responsibility material should be disclosed as a matter of course.” The advice added: “That material will concern a number of ministers still in office, and potentially in the same office. On any view, it will be extremely recent and of the greatest political sensitivity.” The government does not routinely retain WhatsApp messages between ministers and officials unless they contain government decisions. No 10 refused to comment on whether Sunak and current members of the government have yet been asked to hand over their correspondence and documentation in full to the inquiry. John Bell, a leading government adviser during the pandemic, said Hallett should be able to see communications between senior government figures. He added: “First of all, give her access. These are people who are working for the public. If there’s something deeply private and personal they shouldn’t have been using their official context for that. This should all be accessible to the inquiry. But then the inquiry should be a bit careful that they don’t get sucked into a load of sideshows which are not really central to what they are trying to do, but they’ll be able to work that out.” Others to question the government’s actions include Conservative MP Caroline Nokes, who said the apparent “reluctance” by the government to hand over what was requested “seems a nonsense”. Speaking to TalkTV, she added that as much contemporary evidence as possible was vital to ensuring the inquiry could look into serious issues about the handling of the pandemic. She said Hallett “doesn’t look like a woman who’s about to roll over … probably rightly so” and added there would be “less pain for the government if they hand [the files] over quickly”. Labour said the situation had the “whiff of a cover-up” while the Lib Dems said this “dog ate my homework-type excuse from the government simply doesn’t stand up to scrutiny”. Susie Flintham, a spokesperson for the Covid-19 Bereaved Families for Justice campaign group, said the lengths the Cabinet Office is going to in order to prevent Johnson’s material being shared “should alarm everyone”. “This inquiry needs to get to the facts if it is to learn lessons to help save lives in the next pandemic. So why are the Cabinet Office standing in their way? Our members are wondering what they are hiding?” she added. Bob Kerslake, a former head of the civil service, told the BBC there was “some cover-up going on here to save embarrassment of ministers”, as well as the Cabinet Office in his view wrongly “fighting for a principle of confidentiality”. Jonathan Jones, a former government lawyer, suggested the government’s actions were ultimately not likely to work because Hallett’s inquiry has wide powers. “It might be viewed as an attempt to avoid handing over material which the government would prefer not to, but it’s not likely to work because ultimately it will be for the courts to decide. So if it’s a cover-up, it’s not likely to be successful,” he said. The controversy appears to have done nothing to smooth tensions between Sunak’s government and Johnson, after the former prime minister was reported to police last week by Cabinet Office officials after the government-appointed lawyers found potential evidence of more lockdown-breaking parties in his diaries. Johnson has denied this. The prime minister and his predecessor were meant to have peace talks this week over issues such as the Covid inquiry and Johnson’s long-awaited peerages list but this phone call has been cancelled. Sunak said on Tuesday the government was cooperating fully with the Covid inquiry and No 10 denied the suggestion of a cover-up, with the Cabinet Office highlighting 55,000 documents, 24 personal witness statements and eight corporate statements given to the Covid inquiry. The government argues that handing over unredacted notebooks and WhatsApp messages would be an affront to the privacy of officials and ministers, as well as hindering policy discussion. However, the inquiry has also requested proof in the form of testimony from a senior official that the government does not hold any WhatsApp messages or notebooks from the former prime minister. It asked for records of searches conducted and correspondence with Johnson to be provided. It is now two weeks before the first public evidence sessions and a new schedule released by the inquiry shows some matters such as vaccines, procurement and care homes will not be concluded until 2026 – after the next election.