Defence minister Anna Soubry has denied shouting "sanctimonious cunt" at Ed Miliband in the House of Commons.
However, leaked footage obtained by BuzzFeed News appears to show that similar words were indeed said in the chamber during Prime Minister's Questions. Only MPs are allowed on to the floor of the House of Commons.
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The clip was shot for Inside the Commons, a BBC documentary on the inner workings of parliament with unprecedented access.
The footage in question was due to be included in Monday night's episode and journalists had been alerted to the existence of the insult in advance by press officers working for the programme.
However, the section was edited out at the last minute after a Daily Mail journalist told Conservative MP Soubry that the newspaper intended to identify her as the likely source of the insult. She is understood to have complained to the BBC, and the organisation made the decision to remove this section from broadcast at the last minute.
In the original clip, director Michael Cockerell intones: "Official television coverage, even though it is heavily restricted, has fuelled public antagonism to MPs. But our cameras have witnessed the unsanitised version in which MPs sometimes use the most offensive language."
The camera then shows Soubry, who has ministerial responsibility for the welfare of soldiers, shouting at the same time as what sounds like "sanctimonious cunt" is heard on the audio track.
The footage is not conclusive and many MPs often shout loudly throughout Prime Minister's Questions.
BuzzFeed News has requested a comment from Soubry but she has yet to respond. She has strongly denied using the phrase, according to the Daily Mail, which first reported the story.
Soubry told the newspaper that the allegation she shouted "sanctimonious cunt" was completely unfounded, saying:
I beg your pardon. I can be heard saying what? No. Absolutely not. Never. Never. And if you print that I will sue you because I would never.
The C-word? No absolutely not, I would never use that word and I would never use it in the House of Commons and I would certainly never use it. … I'm not having that. I can absolutely assure you I have never used language like that and I can equally assure you on the back row nobody, we wouldn't think of shouting a word like that, the foulest word.
I'm now going to ring both the press office here and at HQ, and I'm going to ring my solicitor. I would never say that and that's an extremely, extremely serious allegation. Never ever. That word is never used in the House. Outrageous.
Director Michael Cockerell went even further, telling the Daily Mail that he was not aware of the clip: "I don't know what you're talking about. I don't recognise what you're talking about. Anything you're talking about is not in the programme."
Watch the full clip with Cockerell's voiceover here:
Anna Soubry has clarified her stance and told the Nottingham Post that she actually she said "sanctimonious rubbish" in the clip.
Citing BuzzFeed News' leaked footage, she said: "If you go on Twitter, you will hear the unedited version of what I really said and it's clear I said "sanctimonious rubbish".
Meanwhile, the BBC issued a statement denying they removing the clip after pressure from Soubry:"The BBC and the programme makers had complete control over all editorial decisions. Changes are often made to programmes for editorial reasons in the lead up to broadcast, as was the case with this episode, but we did not receive any external pressure.”