Prime Minister Boris Johnson and Chancellor Rishi Sunak will be fined by the police for attending parties during the lockdown.
No 10 confirmed the pair had received notification from the Metropolitan Police that they would be given fixed penalty notices.
Labour leader Sir Keir Starmer called for the two politicians to resign.
The Met is investigating alleged Covid law-breaking at 12 gatherings in Whitehall and Downing Street.
So far, more than 50 fines have been handed out.
The police said they would not be naming all of those who received the fines, but the government had promised to reveal if Mr Johnson and Mr Sunak were among them.
- Downing Street apologises to Queen over lockdown parties
- Boris Johnson is facing more calls to resign amid parties row
A No 10 spokesman said they had not been informed which event the fine was linked to.
But Sir Keir said it showed the Conservatives were “totally unfit to govern”, adding: “Britain deserves better.
“Boris Johnson and Rishi Sunak have broken the law and repeatedly lied to the British public. They must both resign.”
Liberal Democrat leader Sir Ed Davey called for Parliament – which is currently on its Easter recess – to be recalled to hold a no confidence vote in the prime minister.
He added: “This is a government in crisis neglecting a country in crisis.”
