A former close ally of UK Prime Minister Boris Johnson appears set to blame him for thousands of coronavirus deaths.
Dominic Cummings, the prime minister's former chief of staff, left government last year and this weekend wrote a blog including a series of allegations against Mr Johnson.
On Sunday the former adviser was ready to slam Mr Johnson's performance during the pandemic and to accuse him of being too slow to close borders and impose a lockdown when he appears at a parliamentary committee hearing next month, The Sunday Times reported.
"Dominic has copies of everything and knows where all the bodies are buried," an ally of Mr Cummings was quoted as saying.
"He was pushing the prime minister hard to lock down sooner in the autumn and he has lots of evidence that shows that his decision to delay led to devastating consequences."
As a glut of leaks and counter leaks are made public, Mr Johnson has found himself caught up in ethics complaints and calls for a government-wide inquiry.
Leaked texts appear to show Mr Johnson agreeing to "fix" a tax issue for vacuum magnate James Dyson's staff, brought into the UK to work on the government's drive to mass-produce ventilators to help with the pandemic.
Mr Cummings resigned last year after a tumultuous period as Mr Johnson’s chief adviser in which he clashed with officials, ripped up conventions of government and sparked a national outcry with a 400-kilometre road trip at the height of the first pandemic lockdown.
Accusations from Mr Cummings are highly significant as he was at the heart of government and had a key role in Britain's exit from the European Union, which ultimately helped Mr Johnson win a landslide general election victory in December 2019.
The UK has recorded more than 125,000 deaths in two fierce waves of infections and is only now lifting its lockdown measures.
Mr Cummings' blog post itemised a succession of alleged failings by Mr Johnson and his current senior team.
The blog questions Mr Johnson's integrity and competence, alleges he wanted an ongoing inquiry over lockdown leaks shut down, and claims he considered trying to get political donors to pay for a refurbishment of his Downing Street flat.
International Trade Secretary Liz Truss said on Sunday that Mr Johnson paid for renovations to his Downing Street flat "from his own pocket".
But she refused to answer five times when asked if money from a donor had initially been received to pay for expenses.
"My understanding is the costs have been covered by the prime minister and everything has been fully declared by the rules," she said.
A Downing Street spokesperson said: "At all times, the government and ministers have acted in accordance with the appropriate codes of conduct and electoral law."
Mr Cummings is scheduled to give evidence to the joint investigation of the health and science select committees into the government's handling of the Covid pandemic on May 26.