Dominic Cummings, the former chief adviser to Boris Johnson, has published a series of expletive-laden messages which appear to show the Prime Minister describing Health Secretary Matt Hancock as "totally hopeless."
In a lengthy blog post, Mr Cummings also attacks Mr Hancock for "openly lying" about the government's failings.
It follows appearances by both men in front of Parliament's health committee, which is investigating the handling of the coronavirus pandemic in the UK.
From London, Benji Hyer reports.
IN: Hancock SOT
OUT: SOC
DUR: 55 secs