The Government will now fight a legal battle amid demands for the release of Boris Johnson's WhatsApp messages, diaries and notebooks for the Covid Inquiry.

The Cabinet Office announced that it was seeking a judicial review into inquiry chair Baroness Hallett's demands for the release of documents for inquiry.

The Office, which is a ministerial department supported by 26 agencies and public bodies, said the requested materials were “unambiguously irrelevant”.

In a letter, released after the 4 pm deadline to hand over information, the Cabinet Office said it had provided “as much relevant information as possible, and as quickly as possible” in line with the order.

The Comet: (Andrew Boyers/PA Wire) The Cabinet Office is now seeking a judicial review into demands by the Covid Enquiry for Boris Johnson's WhatsApp messages(Andrew Boyers/PA Wire) The Cabinet Office is now seeking a judicial review into demands by the Covid Enquiry for Boris Johnson's WhatsApp messages (Image: PA)

The letter said of the refusal to hand over the Boris Johnson materials: “The Cabinet Office has today sought leave to bring a judicial review.

"We do so with regret and with an assurance that we will continue to co-operate fully with the inquiry before, during and after the jurisdictional issue in question is determined by the courts, specifically whether the inquiry has the power to compel production of documents and messages which are unambiguously irrelevant to the inquiry’s work, including personal communications and matters unconnected to the Government’s handling of Covid.”

The Government said that there were "important issues of principle at stake" affecting the rights of individual people and the conduct of government.

This comes after the Cabinet Office argued that it did not have the documents (with the exception of his ministerial diaries). However, the former Prime Minister claimed to have handed the materials over.

In a statement to the inquiry, senior civil servant Ellie Nicholson said that Johnson's lawyers had failed to provide a “substantive response” to a request from the Cabinet Office for his old mobile phone.

What is the Covid Inquiry?

The Covid Inquiry has been set up to examine the UK's response to the Covid-19 pandemic.

The inquiry's website states that the reason behind this is to "learn lessons for the future".

The inquiry is interested in investigating the political and administrative decisions made by the UK Government as well as examining vaccines, and therapeutic and anti-viral treatments.

Why is the Covid inquiry demanding Boris Johnson's WhatsApp messages?

The inquiry is interested in investigating the conduct of the UK Government during the pandemic.

The inquiry's head Baroness Hallett insists that these messages and other materials are relevant to the investigations as the messages cover Boris Johnson's time as Prime Minister.