British Prime Minister Boris Johnson has defended his botched bid to overhaul parliament's standards system that prompted a weeks-long sleaze crisis for the ruling Conservatives, as he faced a grilling from lawmakers on Wednesday.

With opposition parties on the attack and rank-and-file Tory MPs deeply unhappy, the embattled British leader admitted he had made a "mistake", as senior colleagues quizzed him for two hours at a scrutiny session held three times a year.

That came shortly after angry exchanges with Labour leader Keir Starmer, and, unusually, House of Commons Speaker Lindsay Hoyle, over accusations of improper conduct, and before he met Conservative lawmakers for a separate inquisition.

Johnson's gruelling day followed several weeks of controversy kickstarted by his failed attempt to overhaul the internal system policing MPs, just as Tory Owen Paterson faced suspension over lobbying ministers for two firms that had him on the payroll.

Owen Paterson was found to have breached parliamentary rules. Photo: AFPOwen Paterson was found to have breached parliamentary rules. Photo: AFP

"It was a total mistake not to see that Owen's breach of the rules... made any discussion about anything else impossible," Johnson told parliament's most senior cross-party watchdog committee.

"The intention genuinely was not to exonerate anybody. The intention was to see whether there was some way in which, on a cross-party basis, we could improve the system.

"In retrospect, it was obviously mistaken to think that we could conflate the two things," Johnson added, adding that he regretted the move.

'I'm in charge!'

Hours earlier, Starmer branded Johnson a "coward" for refusing to apologise for his role in the saga, a remark the Labour leader later withdrew.

Johnson also clashed with the normally mild-tempered Hoyle over his behaviour during weekly "prime minister's questions", as he tried to turn the tables by demanding answers from Starmer.

"You may be the prime minister of this country, but in this House, I'm in charge!" Hoyle bellowed, ordering the British leader to "sit down".

Westminster has been consumed since late October by the row about MPs supplementing their publicly funded salaries with lucrative second jobs, stoking accusations of conflicts of interest.

Paterson's conduct soon became overshadowed by revelations that numerous other MPs had high-paying second jobs, in particular lawyer and former attorney general Geoffrey Cox.

He has been accused of using his parliamentary office for outside legal work, which has netted him more than £6 million ($8 million, 7 million euros) since becoming an MP in 2005, on top of his annual MP's salary, currently around £82,000.

Paterson has since resigned from parliament, while Cox denies breaking the rules.

British lawmakers are permitted to hold outside roles, as long as they declare them, but are not allowed to use their parliamentary offices or resources for such work.

Paid lobbying is also forbidden, with accusations of wrongdoing probed by parliamentary standards watchdogs.

'Unbelievable'

After a barrage of negative headlines and plummeting poll ratings, Johnson tried to get on the front foot Tuesday by backing proposals to bar lawmakers from acting as paid political consultants and advisers.

The move came as Labour unveiled plans for a Commons vote on banning MPs from such roles as well as being paid directors under a strict timetable, which Starmer said had forced Johnson's hand.

The Labour plan lost by 51 votes late Wednesday, with lawmakers instead backing a government amendment calling for a parliamentary committee to propose reforms of a code of conduct for MPs by early next year.

The opposition criticised that as "watered down warm words" and still open to interpretation, and there is also disquiet over its intent in Tory ranks.

"Frankly, he just doesn't get it," Starmer said shortly after the vote.

"It is unbelievable that after the last few weeks the prime minister has whipped his MPs yet again to vote down a plan of action on standards," he added.

At a meeting of his backbench lawmakers Wednesday evening, Johnson reportedly faced discontent.

Laura Kuenssberg, the BBC's political editor, said one attendee had texted her afterwards to say he "looked weak and sounded weak... (his) authority is evaporating".

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