Douglas Ross has said Boris Johnson must resign as Prime Minister if he has been found to have broken covid rules during the first lockdown.
The Scottish Conservative leader said Johnson doesn't need to wait for an investigation by senior civil servant Sue Gray in order to tell the House of Commons whether he was at a Downing Street garden party on May 20, 2020.
The attack by Ross came after ITV revealed Martin Reynolds, Johnson's Principal Private Secretary, invited around 100 employees to the 'bring your own booze' gathering during lockdown.
The PM and his wife Carrie were widely reported to be at the party in the garden - but there had been no confirmation from Johnson himself.
Police are in contact with the Cabinet Office over the claims, which came to a head on Monday night.
Ross told Sky News: "If he has breached his own guidance, if he has not been truthful then that is an extremely important issue.
"As I've said previously, if the Prime Minister has misled parliament then he must resign.
"People are furious, I'm furious. People across Scotland and across the United Kingdom are furious.
"This email went out to about 100 people inviting them to a party when no one else was allowed to do that, in fact, the government guidance was very clear in England that you could only meet up with one other person from another household.
"I can understand the fury, the anger and the rage."
He added: "So it's not pre-judging Sue Gray 's inquiry to tell the public for the Prime Minister to come forward and say if he was at the party or not.
"That's a crucial question that won't in any way undermine Sue Gray's investigation.
"It will let the public know right now if he was there or not. It's a crucial question that shouldn't have to wait to Prime Minister's Questions tomorrow.
"We should hear the answer right now."
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