U.K. lawmakers announced on Friday they will question former prime minister Boris Johnson over whether he lied about "Partygate", in a probe that could trigger his removal as a member of parliament.
In an interim report released after eight months of work, parliament's watchdog privileges committee said the evidence so far undermined Mr. Johnson's pleas of innocence to the House of Commons.
"The evidence strongly suggests that breaches of [COVID lockdown] guidance would have been obvious to Mr. Johnson at the time he was at the gatherings," the report stated.
Described as a summary of the investigation ahead of Mr. Johnson's questioning, it added "there is evidence that the House of Commons may have been misled" on several occasions.
The committee said the ex-Conservative leader had agreed to give public evidence in the week beginning March 20.
Mr. Johnson, who resigned as prime minister last summer after "Partygate" and other scandals, insisted the report vindicated him.
"There's absolutely nothing to show that any adviser of mine or civil servant warned me in advance that events might be against the rules," he told broadcasters.
"I believed what we were doing was implicitly within the rules."
Mr. Johnson repeatedly denied in parliament that he or his staff had breached his own COVID lockdown laws by holding boozy gatherings in Downing Street.
But police issued fines to dozens of aides after a criminal probe, and Mr. Johnson became the first serving UK prime minister found to have broken the law over one of the gatherings.
The seven-member privileges committee comprises four Conservatives, two Labour MPs and a Scottish National Party lawmaker.
If it ultimately concludes that he deliberately misled the House of Commons, it could recommend various sanctions for all MPs to vote on.
They included a suspension of 10 sitting days or more, which would trigger a petition to oust Mr. Johnson as a lawmaker.
A by-election for his west London seat would then be held if 10% of registered voters there sign it.
The developments come as Mr. Johnson and his allies decry the news on Thursday that senior civil servant Sue Gray, who conducted the government's own probe into "Partygate", has quit to work for the leader of the opposition Labour party.
Linking the matter to the committee probe, Mr. Johnson said it was "surreal" that the panel planned to rely on evidence "culled and orchestrated" by Ms. Gray.
Her report found "a failure of leadership and judgement" in Mr. Johnson's Downing Street operation over the controversy, but the committee insisted it had its own evidence.
It cited WhatsApp messages, including one from a top aide who said an excuse offered by staff instead "blows another great gaping hole in the PM's account".
Facing questions about Ms. Gray's hiring, Labour leader Keir Starmer tried to keep the focus on his former Tory rival.
"I think Boris Johnson needs to confront the evidence that is there in front of him, and everybody can see that evidence," he said.