The official Twitter account for the UK Civil Service has accused the Government of being “arrogant and offensive” and “truth twisters”.

In a now-deleted tweet, the account wrote after Sunday’s daily Downing Street press conference: “Arrogant and offensive. Can you imagine having to work with these truth twisters?”

The tweet was up for approximately 12 minutes before it was removed, and was retweeted more than 32,000 times.

The tweet was up for approximately 12 minutes. (Twitter/PA)

The Government confirmed an investigation has been launched into who posted the “unauthorised tweet”.

Author JK Rowling responded: “When you find out who it was, let us know. I want to give them a year’s salary.”

Although the message does not name any individuals, it appears to reference Prime Minister Boris Johnson’s defence of top aide, Dominic Cummings, at today’s conference.

Responding to claims Mr Cummings had travelled 260 miles to County Durham during the peak of the lockdown, Mr Johnson said he had “acted responsibly, legally and with integrity”.

References to the daily conference are the top 10 trends on Twitter this evening, with opposition MPs also responding to the speech given by the Prime Minister.

Labour leader Sir Keir Starmer tweeted: “This was a test of the Prime Minister and he has failed it.

“It is an insult to sacrifices made by the British people that Boris Johnson has chosen to take no action against Dominic Cummings.

“The public will be forgiven for thinking there is one rule for the Prime Minister’s closest adviser and another for the British people.

“The Prime Minister’s actions have undermined confidence in his own public health message at this crucial time.

“Millions were watching for answers and they got nothing. That’s why the Cabinet Secretary must now launch an urgent inquiry.”

Westminster leader for the SNP, Ian Blackford – who has been vocal in his criticism of Mr Cummings today, said the Government’s response was a “failure of leadership”.

He tweeted: “Boris Johnson told us to stay at home and to isolate if we had Covid-19. There was no caveat that this does not apply to Dominic Cummings.

“By supporting Cummings at his press conference Boris Johnson displays a failure of leadership and undermines his own public health messages.”

Labour MP Jess Phillips questioned the claims that Mr Cummings “followed the instincts of every father”.

She tweeted: “The instincts of most other fathers in the country was to look after their partner and children at home. Bad fathering guys.”

David Warburton, the Tory MP for Somerton and Frome, said he was “unconvinced” by Boris Johnson’s defence of Dominic Cummings.

“As much as I despise any baying pitchfork-led trials by social media, I’m unconvinced by the PM’s defence of #Cummings,” he tweeted.

“We’ve all been tasked with tempering our parental, and other, instincts by strictly adhering to Govt guidance.”

Dominic Cummings left Number 10 Downing Street just after 6pm, and gave no response to reporters’ questions when as he drove away, six hours after first arriving.