Covid Inquiry chairwoman Baroness Hallett on Tuesday extended a deadline for the Government to hand over unredacted documents including Boris Johnson WhatsApp messages until 4pm on Thursday.
But she rejected a request from the Cabinet Office for a longer extension until Monday June 5.
She also demanded a statement from a senior civil servant “verified by a statement of truth” to explain the Cabinet Office’s insistence that it does not have in its possession Mr Johnson’s Whatsapp messages or notebooks.
It comes, as Rishi Sunak said on Tuesday the Government is“confident in the approach” it is taking in refusing to hand over unredacted documents.
However, the Prime Minister also said it was “carefully considering its position” as the clock ticked towards an initial 4pm deadline on Tuesday to resolve the row or risk court action.
Mr Sunak was said to have sailed into “untested legal waters” over the Government’s clash with the Covid inquiry.
The Prime Minister faced a growing storm over the requested release of unredacted WhatsApp messages and diaries belonging to Mr Johnson, as well as other communications involving other ministers and officials.
The Government has been insisting that it has no duty to disclose material which it regards as “unambiguously irrelevant” to the Covid probe.
But Baroness Hallett, a former Court of Appeal judge, says it is for inquiry team to decide what is relevant or not to its investigation.
On a visit to Kent on Tuesday morning, Mr Sunak said: “I think it’s really important that we learn the lessons of Covid and that’s why the inquiry was established.
“We want to make sure that whatever lessons there are to be learned are learned and we do that in a spirit of transparency and candour.”
He added: “With regard to the specific question at the moment, the Government is carefully considering its position but it is confident in the approach that it’s taking.”
The row was sparked by a legal request sent by the inquiry on April 28 for a number of materials, including unredacted WhatsApp messages and diaries belonging to the former Prime Minister between January 2020 and February 2022.
Human rights barrister Adam Wagner told Sky News: “The width of the request is I think unprecedented, or at least close to unprecedented in a public inquiry.
“But I can entirely see the logic because the Covid pandemic itself was unprecedented.
“We are in, legally speaking, untested waters.”
He added that the Government would be worried about setting a precedent of having to hand over a wide range of documents, which it may consider irrelevant, to future inquiries so would have been considering taking the “public risk” of challenging the Covid probe’s request.
Former head of the Civil Service Lord Kerslake told BBC Radio 4’s Today programme: “There’s some cover-up going on here to save embarrassment of ministers. But there’s also the Cabinet Office fighting for a principle of confidentiality.
“I have to say I think they’re misguided on this situation. I actually think it would set a helpful precedent if Lady Hallett prevailed in this fight about the information.”
In May the Cabinet Office pushed back against the request, which was made under section 21 of the Inquiries Act 2005 and which also applies to messages from former adviser Henry Cook.
In a ruling last week, Lady Hallett rejected the argument that the inquiry’s request was unlawful and claimed that the Cabinet Office had “misunderstood the breadth of the investigation”.
The crossbench peer stressed it was her role, not that of the Government, to decide what was relevant to her inquiry.
She also highlighted that passages initially considered by the Cabinet Office to be irrelevant included discussions between the then PM and his advisers about the enforcement of Covid regulations by Scotland Yard during demonstrations following the murder of Sarah Everard.
She explained those redactions had now been withdrawn but “it was not a promising start”.
Refusing to comply with the request would lead to a spiralling egal clash with the official inquiry, raising the possibility of ministers seeking a judicial review of the probe’s powers, or the inquiry taking the case to the High Court. with the threat of criminal sanctions.
The clash comes just weeks before the first public evidence sessions are expected to be held.
The Cabinet Office has already provided more than 55,000 documents, 24 personal witness statements and eight corporate statements to the inquiry.
But Lady Hallett, in last week’s ruling, stressed that the requested documentation was of “potential relevance” to the inquiry’s “lines of investigation”.
She said: “I may also be required to investigate the personal commitments of ministers and other decision-makers during the time in question.
“There is, for example, well-established public concern as to the degree of attention given to the emergence of Covid-19 in early 2020 by the then Prime Minister.”
A Cabinet Office spokesman said: “We are fully committed to our obligations to the Covid-19 inquiry.
“As such, extensive time and effort has gone into assisting the inquiry fulsomely over the last 11 months.
“We will continue to provide all relevant material to the inquiry, in line with the law, ahead of proceedings getting under way.”
According to the notice seeking the unredacted messages, the inquiry is requesting conversations between Mr Johnson and a host of government figures, civil servants and officials.
The list includes England’s chief medical officer Professor Sir Chris Whitty, as well as then-chief scientific adviser Sir Patrick Vallance.
Messages with then-foreign secretary Liz Truss and then-health secretary Matt Hancock are also requested, as well as with former top aide Dominic Cummings and then-chancellor Mr Sunak.
The inquiry had also asked for “copies of the 24 notebooks containing contemporaneous notes made by the former Prime Minister” in “clean unredacted form, save only for any redactions applied for reasons of national security sensitivity”.
