Wales' First Minister Mark Drakeford reacted to the latest news of a party at Downing Street with a combination "despair and disgust".
Boris Johnson was facing fresh allegations of breaking coronavirus rules after Downing Street admitted he had a birthday celebration inside No 10 during the first lockdown.
Downing Street conceded staff "gathered briefly" in the Cabinet Room following a meeting after it was alleged 30 people attended and shared cake despite social mixing indoors being banned.
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ITV News reported the Prime Minister's wife, Carrie Johnson, had organised the surprise get-together complete with a chorus of "happy birthday" on the afternoon of June 19 2020. Interior designer Lulu Lytle admitted attending but insisted she was only present "briefly" while waiting to talk to Mr Johnson about the lavish refurbishments she was carrying out to the couple's flat above No 11.
Speaking to BBC Radio 4 on Tuesday, Mark Drakeford said: "I reacted with despair that this is where our country has ended up after this awful experience. Disgust at the things that went on in Downing Street and the way that the Tories turn out people to try to justify it. Saying it was 'only a party'... only two people were allowed to meet indoors.
"'It only lasted 10 minutes'... you weren't meant to meet for 10 seconds. Amongst the hardest letters that I have read during the whole pandemic have been from people telling me they had to attend a funeral where only eight people were able to be there, where it didn't last 10 minutes, you weren't able to sing. In Wales, a funeral where you are not able to sing is a really difficult experience, but yet, these people stuck to the rules, it was hard but they did it.
"I don't think the Prime Minister had the moral authority to lead a country like the United Kingdom, that is what all this exposes for me. You can't ask people to do difficult and upsetting things that you are so patently unwilling to do yourself."
The First Minister was also asked if coronavirus had separated people in the United Kingdom. Mr Drakeford said: "I believe in the United Kingdom. There is a compelling case to be made that people would want to be a member of that sort of United Kingdom. The pandemic has drawn to the surface the fact that for 20 years in Wales we have been making our own decisions.
"Doing things in a way that allows us to craft the solutions that meet our own circumstances. In some ways, I don't think it has changed the fundamentals, but it has drawn it to the surface, made them visible.
"We have stumbled our way through the coronavirus experience, with a make and mend arrangements. That will not sustain the United Kingdom into the future. We need a set of intergovernmental arrangements that are reliable and respectful and that way we can get round the table together. There is far more we have in common than divides us."
A Downing Street spokeswoman has admitted there was a "gathering" on the Prime Minister's birthday.
She said: "A group of staff working in No 10 that day gathered briefly in the Cabinet Room after a meeting to wish the Prime Minister a happy birthday. He was there for less than 10 minutes."
ITV news also reported that later that evening family friends were hosted upstairs to further celebrate the Prime Minister's 56th birthday in his official residence. No 10 said: "This is totally untrue. In line with the rules at the time the Prime Minister hosted a small number of family members outside that evening."
Sir Keir Starmer said the latest revelations were "yet more evidence that we have got a Prime Minister who believes that the rules that he made don't apply to him".
"The Prime Minister is a national distraction and he's got to go," the Labour leader added.
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Sue Gray was understood to have already been aware of the birthday party allegations and therefore their emergence will not further delay the publication of her inquiry, which is still expected this week.
The senior civil servant has been investigating a series of claims of rule-breaking parties in No 10 as Mr Johnson faces calls to resign as Prime Minister, including from some of his own Conservative MPs.
On Tuesday morning, Grant Shapps suggested the public would not consider the Prime Minister's birthday gathering as a party.
The Transport Secretary told BBC Breakfast: "I think most people would think of a party as being an arranged event rather than something where on somebody's birthday in the office that they work in with the people that they always work with, someone says 'it's your birthday here's a cake'.
"But that is for Sue Gray to get to the bottom of, I do agree and understand why - not least from my own personal experience - this would cause upset."
But he said there were "so many other issues" to focus on, including the threat of a Russian invasion in Ukraine.
Mr Shapps said: "Those are the issues that we... that he is still focused on and the issues that we really should be focused on ourselves because things like that are really going to matter to our lives in a way that events of 20 months ago may not."
