A defiant British Prime Minister Boris Johnson on Wednesday vowed to "keep going" as he appeared before a hostile crowd of parliamentarians, not only from the Opposition benches but from within his own Conservative Party, just hours after the big blow of losing his Chancellor Rishi Sunak and Health Secretary Sajid Javid in quick succession.

Johnson, 58, appeared at the weekly Prime Minister's Questions (PMQs) in the House of Commons amidst mounting pressure on him to resign over the handling of allegations of sexual misconduct by a member of his government.

A flurry of junior ministerial and government aide resignations, totalling 18, continues to hit the embattled leader even as Javid made a speech in the Commons calling upon his former Cabinet colleagues to reconsider their decision to continue to back Johnson because "enough is enough".

"The job of a Prime Minister in difficult circumstances, when you've been handed a colossal mandate, is to keep going, and that's what I am going to do," said a defiant Johnson, in response to repeated demands for him to quit.

"It's exactly when times are tough, that when the country faces pressures on the economy and pressures on their budgets and when we have the biggest war in Europe for 80 years, that is exactly the moment that you'd expect a government to continue with its work, not to walk away, and to get on with the job," he said.

Opposition Leader Sir Keir Starmer attacked Johnson over his handling of the latest scandal to hit Downing Street, reading out the accusations levelled at his disgraced former Deputy Chief Whip as a "reminder to all those propping up this Prime Minister just how serious the situation is".

In fiery exchanges at PMQs, the Labour leader said the list of resignations had left him with a "Z list cast of nodding dogs" on his frontbench, adding the "sinking ships are fleeing the rat".

Several on the Conservative benches also piled the pressure, with former Brexit minister David Davis, who had told Johnson in the name of God, go just six months ago, reiterated his demand: "Do the honourable thing [and] put the interests of the nation before his own interests and before, in his own words, it does become impossible for government to do its job."

There is further grilling in store for Johnson when the Parliament's Liaison Committee questions him on topics including integrity in politics.

The exit of Sunak and Javid has left the Conservative Party leader in a precarious position as further resignations are expected.

Earlier on Wednesday, Will Quince, who was sent out to defend No. 10 Downing Street's appointment of Chris Pincher as Deputy Chief Whip just hours before Johnson admitted his mistake in appointing him to a government job, resigned as an education minister.

Soon after, Robin Walker resigned as the schools minister, warning against a "worrying narrowing of the broad church that I believe any Conservative government should seek to achieve". It came as Tory MP Laura Trott quit as a ministerial aide at the transport department saying the government has lost trust, adding to a growing number of aides who have similarly stepped down.

However, Johnson has moved swiftly to fill the top jobs with Iraqi immigrant minister Nadhim Zahawi stepping in as UK Chancellor of the Exchequer and Steve Barclay as Health Secretary.

Under current rules Johnson is safe from another leadership challenge until next summer. But the executive of the 1922 Committee can change the rules whenever it wants, the British media reports said.

"The team in government today is the team that will deliver," said Zahawi, in his first set of interviews in the new post.

He urged his Cabinet colleagues to unite behind Johnson, saying: This is a team game, and you play for the team, and you deliver for the team."

It follows Johnson's apology on Tuesday, after days of changing messages from Downing Street over the hiring and handling of the now-suspended Chris Pincher, who quit as Deputy Chief Whip in charge of Tory party discipline last week after being accused of groping two men in a private member's club in London.

First to announce his departure was Javid, who in his damning resignation letter said he could "no longer, in good conscience, continue serving in this government".

Sunak followed minutes later, saying the public rightly expected the government to be conducted properly, competently and seriously . More junior ministers and ministerial aides followed, with more exits expected.

But Johnson's allies have spoken out in his favour, with Culture Secretary Nadine Dorries saying the Prime Minister "consistently gets all the big decisions right", while Brexit Opportunities Minister Jacob Rees-Mogg said his victory at the 2019 general election "should not be taken away from him because a number of people resign".

PTI