The Prime Minister faced questions over the scandal during a visit to Burnley. He was asked whether the MP involved would lose the whip if the allegations were true.

It came as the Attorney General Suella Braverman said a minority of men in Parliament behaved like “animals”.

The Prime Minister said: “I think it’s obviously unacceptable for anybody to be doing that kind of thing in the workplace.

Prime Minister Boris Johnson said the allegations were "unacceptable"

“It would be the same for any kind of job up and down the country, let’s be absolutely clear about that.

“What needs to happen now is that the proper procedures need to be gone through, the independent complaints and grievances procedure needs to be activated and we need to get to understand the facts, but, yeah, that kind of behaviour is clearly totally unacceptable.”

The identity of the MP is the source of much debate in Westminster, with the same few names being mentioned by those in Parliament.

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Earlier Ms Braverman told BBC Radio 4’s Woman’s Hour that if a Tory MP was found to have been watching pornography in the Commons chamber, they should have the whip suspended and face the prospect of being ousted from Parliament.

She said: “I keep running through my mind how and why someone would be so brazen … so reckless, so stupid, so appallingly badly behaved to be watching porn in the workplace, in broad daylight, in the presence of colleagues.

"If the case was proven, there should be a severe reprimand.

“I think that we would really need to see a situation where the whip should be removed – I’m ashamed this person is carrying a Conservative rosette.”

Ms Braverman said the men she had worked with had been “respectful, courteous and supportive”.

“There is, however, a very small minority of men – and it is men – who fall short and there are some bad apples who are out of order, who behave like animals, and are bringing Parliament into disrepute, to be honest,” she said.

Under the Independent Complaints and Grievance Scheme (ICGS), an investigator would examine the case and Parliamentary Commissioner for Standards Kathryn Stone would then make a finding.

In a serious case like this a sanction would normally be decided by the Independent Expert Panel (IEP), which would also hear any appeal.

The IEP could recommend sanctions including expulsion from the Commons or a suspension, which could potentially trigger a by-election under the recall process if it is for longer than ten sitting days.

Only witnesses to the pornography-viewing could make a complaint about the MP under the ICGS.

Health secretary Sajid Javid said: “There have been several instances of inappropriate and sexist behaviour recently in Parliament. It is shameful.

“Parliamentarians are public servants and it is their duty to set an example of character and integrity. The culture of Westminster needs to change.”

Defence secretary Ben Wallace said “there’s no place for pornography in any workplace” and highlighted the need for a cultural change at Westminster.

Labour leader Sir Keir Starmer said there was action the Tories could take now, rather than wait for the complaints process to conclude.

Boris Johnson says allegations Tory MP watched porn are ‘unacceptable’ as minister admits some MPs are ‘animals’