John Bercow has been accused of calling the Leader of the House of Commons a “stupid woman” during a foul-mouthed tirade in Parliament.

The Speaker, already facing multiple accusations of bullying, astonished MPs in the chamber on Wednesday as he allegedly muttered that Andrea Leadsom was “f------ useless”.

Mr Bercow faced fresh pressure to quit by MPs who said his behaviour was “unbecoming of his position”.

He did not deny making the comments and has not apologised to Mrs Leadsom, instead blaming his outburst on what he called “an unusual and controversial day” in the Commons in which “strong and differing views” were expressed.

Sources close to Mrs Leadsom are trying to obtain footage of the incident from the video camera that remains focused on the Speaker during debates. A live television broadcast cut away from Mr Bercow to another camera angle seconds before he made the comments.

Mrs Leadsom is said to be “outraged” by the incident and is “weighing up” making a formal request for an investigation to Kathryn Stone, the Parliamentary Commissioner for Standards.

Mr Bercow is also at the centre of a bitter parliamentary power struggle. Tory MPs have alleged that the Speaker is being protected by a cabal of Labour MPs who see him as a useful ally, while also objecting to his apparent willingness to grant opposition members more questions and speaking time in the chamber.