The UK prime minister batted away partygate questions by saying he has already given "vintage and exhaustive answers" just as he came under fresh fire.

Tory MP Paul Holmes resigned as an assistant to Home Secretary Priti Patel, saying he was "shocked and angered" by revelations in a report on the breaches.

He blasted the "deep mistrust" created by the breaking of Covid rules, after four Conservative MPs added their voices to demands for Mr Johnson's resignation.

But Mr Johnson told reporters that he is confident he has enough support within his party.

He sought to further deflect questions when pressed on why he tolerated the culture that saw staff drink so much they were sick, become involved in altercations and abuse security and cleaning staff.

Resigning as a parliamentary private secretary, Mr Holmes said the scandal was undermining his work for constituents in Eastleigh, Hampshire.

"It is distressing to me that this work on your behalf has been tarnished by the toxic culture that seemed to have permeated Number 10," he wrote on his website.

The resignation marks another blow after four Tories went public with resignation demands since the damning report laid bare the parties in No 10 at a time when millions were forced to cut off contact with loved ones.

A vote on the Prime Minister's future will be held if 54 of his MPs write that they have lost their confidence in their leader.

Twenty Tories have publicly called for his resignation so far, with many critics holding back due to the war in Ukraine.

Australian Associated Press