Boris Johnson and his team have faced repeated questions over allegations that No10 staff held two parties during lockdown in 2020.
Insiders allege that the prime minister attended one of the gatherings on November 27 when meeting indoors or in private gardens was not allowed under pandemic rules.
A separate one the PM did not attend allegedly took place on December 18 when London was under Tier 3 restrictions - banning mixing between households.
When asked about it previously, the prime minister did not deny reports that members of his team held a party in Downing Street on December 18.
However, No10 ramped up its rebuttal today and insisted that there was not a party held on the premises.
Asked if Downing Street had spoken to anyone at the party, a spokesman for the prime minister replied: “As the press secretary set out at a number of occasions, when questioned about this originally, there was not a party and the covid rules were followed at all times.”
Asked how they established the rules were not broken, he replied: “It’s simply the case that guidance has been followed at all times.”
Pressed how they established that, the spokesman added: “I don’t need to get into the positions we’ve taken, it’s simply just a statement of fact.”
Asked how it was a statement of fact if they had not investigated, he replied: “I’m not going to get into internal matters. As I said, guidance has been followed at all times.”
It comes after policing minister Kit Malthouse said he would “expect the police to have a look” if a complaint had been made but that he took at face value Downing Street’s insistence that no rules had been broken.
Meanwhile, deputy prime minister Dominic Raab said yesterday that having a party would have been wrong, but described the reports as “unsubstantiated”.
Raab said: “Until there is something substantiated, until it is more than anonymous sources, I think we are chasing shadows. If there is a breach of the rules, there is a breach of the rules. But I don’t know the full facts because I wasn’t there.”
However, he was ridiculed after telling the BBC’s Andrew Marr show that the police “don’t normally look back and investigate things that have taken place a year ago”.
Separately, the prime minister’s spokesman also confirmed that Downing Street intends to hold a Christmas party for staff this year.
He added: “We haven’t confirmed any dates at the moment. I think there is an intention to have a Christmas party this year.”
This article originally appeared on HuffPost UK and has been updated.