Dominic Cummings is threatening to exert revenge on Boris Johnson by revealing a Downing Street document on the prime minister’s COVID lockdown strategy.

Unleashing a blizzard of often erratic messages on Twitter, the maverick former No 10 aide claimed he has “the only copy of a crucial historic document from COVID decision-making”.

And as the government faces accusations that being too slow to ban flights to the UK from India caused a surge in the new Indian variant, he also hit out at “our joke borders policy”.

Mr Cummings, who was the prime minister’s policy guru and close confidant until he was ousted in a vicious power struggle late last year, is due to make a potentially blockbuster appearance before MPs next week.

He is scheduled to give evidence next Wednesday to a joint inquiry into the government’s handling of the pandemic being conducted by the all-party health and social care and the science and technology committees.

As well as stirring up mischief, Mr Cummings’ Twitter blitz will be seen by Tory loyalists as a backlash against allegations from No 10 insiders that he was responsible for embarrassing leaks about who paid for the costly makeover of the PM’s Downing Street flat.

In a 1,000-word blog last month, Mr Cummings accused Mr Johnson of “falling so far below the standards of competence and integrity the country deserves”.

More on Boris Johnson

With a public inquiry now promised by the PM, Mr Johnson and Mr Cummings – once the closest of allies on Brexit and election campaigning – now appear to be sworn enemies and the PM’s allies fear the former aide is hellbent on destroying his ex-boss.

In his tweet threatening trouble for the PM in his committee appearance, Mr Cummings said: “I’ve got the only copy of a crucial historical document from covid decision-making,”

And then in more light-hearted vein, he went on: “Should I 1/ give it to the Cmte next week / put on blog, b/ auction it … & give the ETH to a covid families charity?”

Please use Chrome browser for a more accessible video player

Health dept was a ‘smoking ruin’ in Spring 2020 – Cummings

Mr Cummings later deleted the tweet offering to auction the document about 45 minutes after posting it, explaining he had “botched options like idiot”.

The threat to reveal a damning document triggered trepidation in the Tory high command and ridicule among Mr Cummings’ critics, with some suggesting the document was the result of his eye test after his notorious explanation for his lockdown-busting trip to Barnard Castle last year.

The tweets were among at least 25 posted by Mr Cummings over a 24-hour period, mostly relating to Mr Johnson’s COVID strategy, with some apparently composed while he was in a waiting room ahead of his first vaccination.

Asked about Mr Cummings’ tweets and his threat to release a top secret Downing Street document, the prime minister’s spokesman gave a frosty response.

“I’m not going to speculate about what information individuals may or may not choose to present at committees,” the spokesman said. “Obviously there are strict rules that are abided by in these situations.”

Among the tweets were allegations about the failure of “pseudo lockdowns” and more on his vendetta against Matt Hancock’s Department of Health, which in a previous select committee appearance he called “a smoking ruin”.

His tweets included: “Remembered Vallance 24/3 amid disaster: will u support taking vaccines out of DH & a new Taskforce, we need different leadership & skills to drive it? CABSEC supported divvying up DH tasks. If not, normal Whitehall process, probably normal result.”

This appeared to be a suggestion that Sir Patrick Vallance, the government’s chief scientific officer, had proposed stripping Mr Hancock’s department of vaccines policy and that this was supported by the former cabinet secretary, Sir Mark Sedwill.

Mr Cummings then wrote: “Success seems to have blinded SW1 to important Qs. a/ We did it much better than Brussels, obviously, but Brussels is not a good comparison.

“How well did we do relative to ‘how well wd General Groves who ran the Manhattan Project have done it?'”.

The Manhattan Project was the US-led race to build a nuclear bomb in World War II.

Mr Cummings also alleged that the government missed an opportunity to start vaccinations last summer.

He tweeted: “I think we’ll conclude we shd have done Human Challenge trials immediately & cd have got jabs in arms summer.

Please use Chrome browser for a more accessible video player

Johnson and Cummings are ‘two boys fighting’

“This is not criticism of the VTF (Vaccines Task Force) which has been constrained in ways they shdnt be. It’s cnctd to b/ where is the public plan for how the VTF will deal with variants?”

Mr Cummings also suggested there had been a cover-up to hide government blunders.

“One of the most fundamental & unarguable lessons of Feb-March is that secrecy contributed greatly to the catastrophe,” he wrote.

“Openness to scrutiny wd have exposed Gvt errors weeks earlier than happened.

“So why are MPs accepting the lack of a public plan now for VTF viz variants? Especially when rumours reach me that the silent entropy of Whitehall is slowly turning VTF back into a ‘normal’ entity?

“The best hedge re a variant escaping current vaccines is PUBLIC SCRUTINY of Gvt plans. This will hopefully show it’s been taken seriously. If not, better learn now that the Gvt has screwed up again than when ‘variant escapes’ news breaks.

“I can think of no significant element of covid response that wd not have been improved by discarding secrecy and opening up. This was symbolised by e.g how COBR cd not be used: a constrained STRAP environment cd not cope with the scale/speed, another important lesson.”

“Having watched classified elements of covid response, Gvt cd make the vaccine plans 99% public without risks, ‘national security’ almost totally irrelevant to the critical parts of the problem, a few things cd be withheld while publishing all crucial parts of the plan.”

Hitting back at Mr Cummings’ claim that border policy is “a joke”, the PM’s official spokesman said: “Obviously, I would reject that. We have some of the strongest border measures in the world.”

On his claim that vaccine trials should have started earlier, the spokesman said: “There are a number of individuals who have different views on actions taken by government during the course of this pandemic.”

And on the claim that the COVID plan was “either non-existent or a disaster”, the spokesman said: “Our approach to this pandemic throughout has been guided by the best scientific data.

“It is an approach that has enabled us to secure early development of vaccines which has now enabled us to move through our roadmap and restore freedoms to the public.”