The claims – rejected as “total nonsense” by the Sunak camp – come as Mr Johnson was warned he could lose taxpayer-funded legal support if he tries to “undermine” the government’s position on the inquiry.
And a leading scientist has attacked Mr Sunak’s “spectacularly stupid” Eat Out to Help Out scheme, as he comes under pressure to share his own messages about the much-criticised policy.
The former PM remains at the centre of an astonishing row as ministers launched a High Court bid to challenge the inquiry’s demand for his unredacted messages and notebooks.
Mr Johnson’s allies claimed Mr Sunak was launching legal action to prevent the release of ministers’ WhatsApps – suggesting he may be “hiding” plots or messages that put his Covid restaurant scheme in a bad light.
One Johnson ally told the Mail on Sunday: “What is Rishi hiding? Is it plotting against Boris with Dominic Cummings? Is it because he himself broke lockdown rules? Or does he fear that his Eat Out to Help Out scheme led to a significant number of deaths?”
They added: “Both Rishi and Boris will give evidence in the autumn, and it will be a gift to Labour. We expect them to set up a war room and use it to beat up Sunak every day.”
A Whitehall source told the newspaper: “The government has taken a judge to court to keep other ministers’ messages secret. Why? What is team Sunak trying to hide? The cover-up office is a shambles and it’s only a matter of time before heads roll.”
But a source close to Mr Sunak told The Independent: “It’s total rubbish – as you can see from the Telegraph’s lockdown files, Rishi Sunak barely uses WhatsApp.”
Asked about the claims by Johnson allies and whether Mr Sunak was trying to hide plots against Mr Johnson, immigration minister Robert Jenrick told Sky News: “No – the issue here is ... should you hand over material to the inquiry which has absolutely nothing to do with Covid.”
Mr Jenrick said it is not “sensible or reasonable” to share material unrelated to Covid – and suggested a compromise was still possible, despite the judicial review. “I hope this can be resolved indeed even before the matter gets to court,” he added.
Bereaved families told The Independent that Mr Sunak should stop trying to “protect himself” and hand over his own WhatsApps so crucial pandemic decisions – including the Eat Out to Help Out scheme – can be scrutinised.
Rivka Gottlieb of the Covid-19 Bereaved Families for Justice UK group said: “It looks like Sunak is protecting himself. It’s indecent to cover things up. I want every relevant person in government to be handing over WhatsApp messages.”
Prof John Edmunds of the London School of Hygiene and Tropical Medicine – a member of the government’s Sage committee – said Eat Out to Help Out was “a spectacularly stupid idea and an obscene way to spend public money”.
The former adviser told The Observer the August 2020 scheme to offer Britons a discount to eat out in restaurants and pubs after the first lockdown was never discussed with scientists.
Meanwhile, it has emerged that Cabinet Office lawyers told Mr Johnson that money would “cease to be available” if he breaks conditions such as releasing evidence without permission.
The former PM vowed to send all his messages to the official investigation directly, circumventing the Cabinet Office. The Sunday Times detailed a letter sent by Cabinet Office lawyers to Mr Johnson last week.
“The funding offer will cease to be available to you if you knowingly seek to frustrate or undermine, either through your own actions or the actions of others, the government’s position in relation to the inquiry unless there is a clear and irreconcilable conflict of interest on a particular point at issue,” it said.
The Cabinet Office’s recent referral of Mr Johnson to police for suspected Covid rule breaches referral promoted a furious former PM to sack his team of government-appointed lawyers and ask for a new team at Peters & Peters law firm.
The Cabinet Office has agreed to keep paying for the legal support, which is needed for the MPs’ privileges committee investigation. But the department warned that funding would “only remain available” if he complied with conditions such as sending the Cabinet Office material for the Covid inquiry for checks by officials.
This is not a good look for the Government. All evidence provided should be unfettered and not restricted by gov censorship - whatever form that may take. https://t.co/bBIufEK91C
— Rt Hon Nadine Dorries MP (@NadineDorries) June 3, 2023
But former culture secretary Nadine Dorries, a staunch ally of Mr Johnson, said it was “not a good look for the government”, saying the messages should not be “restricted by government”.
Tory donor Lord Cruddas, an outspoken backer of Mr Johnson, also urged his ally not to be “held to ransom” by the threat. “Don’t worry Boris Johnson I can easily get your legal fees funded by supporters and crowd funding, it’s easy,” he tweeted.
Mr Johnson wrote to the inquiry’s chair, Baroness Hallett, saying he was sending all the unredacted WhatsApps he had given to the Cabinet Office.
He said he would like to do the same for the messages on an old phone he was told not to use after it emerged the number had been online for 15 years. That device will be crucial, containing discussions before May 2021.
Mr Jenrick acknowledge this week’s warning letter to Mr Johnson, but told Sky News: “There’s absolutely no sense that the government will restrict what Boris Johnson wants to say but if you use taxpayer funds, obviously you should make sure you’re using them appropriately.”
A Cabinet Office spokesperson said the letter from officials “simply reiterates that taxpayer-funded lawyers must be used to aid the Covid inquiry and for no other purpose”, adding: “This letter was intended to protect public funds. It in no way prevents Mr Johnson from providing whatever evidence he wants to.”
The Independent has approached No 10 for comment on claims by Johnson allies.