Theresa May has said she is “angry” at the partygate revelations engulfing Boris Johnson, her successor in Number 10.
Mrs May, who was in Downing Street from 2016 to 2019, made her intervention regarding the scandal in a letter seen by her local newspaper.
She told constituents that “nobody is above the law”, the Maidenhead Advertiser reported.
Reaction as police statement raises fresh questions about partygate report – politics live
May expects ‘full accountability’ if wrongdoing found
“I have said previously that it is vital that those who set the rules, follow the rules. Nobody is above the law,” the newspaper quoted her as writing in the letter.
“This is important for ensuring the necessary degree of trust between the public and government.
“Like so many, I was angry to hear stories of those in Number 10, who are responsible for setting the coronavirus rules, not properly following the rules.”
The letter was sent before the Metropolitan Police announced it was investigating a “number of events” in Downing Street and across Whitehall for potential breaches of COVID regulations.
On Friday, the force revealed it had asked the Cabinet Office inquiry into partygate to only make “minimal reference” to the events it is investigating.
The request has raised doubts about when the inquiry, led by senior civil servant Sue Gray, will be published.
Mrs May said that “if there is evidence of deliberate or premeditated wrongdoing, I expect full accountability to follow”.
Read more: How is the Met Police inquiry into No 10 COVID breaches different to Sue Gray’s?
She added: “All those working at the heart of government should conduct themselves with the highest of standards which befits the work they do, and this applies as much to those working in Number 10 as to other parts of government.”
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Mrs May has been a critic of some of her successor’s policies, making a number of interventions in the Commons.
She chose Mr Johnson as her foreign secretary when she entered Number 10 in the wake of the EU referendum.
But Mr Johnson quit in 2018 over the then-PM’s handling of Brexit.