John Bercow has admitted using the word "stupid" in a row over a senior government minister but stopped short of apologising, insisting his comments were focused on the government's handling of business.
The under-fire speaker said he had not been referring Andrea Leadsom personally during the exchange, as he repeated his criticism of ministers for scheduling a rail statement that took time away from an opposition day debate on the Grenfell Tower fire.
Mr Bercow, a champion of backbenchers, was heard allegedly calling the Commons leader a "stupid woman" and "f****** useless" after prime minister's questions last week.
It comes as the speaker was dogged by allegations of bullying from several senior aides, one of whom said staff were "terrified" by his "explosive and intemperate behaviour".
As critics seized on the row as an opportunity to oust him, Mr Bercow praised Ms Leadsom for her "political ability and her personal character".
He told MPs: "I thought then, as I think now, that this was very badly handled. It was, in particular, very disrespectful both to the House and to the 23 backbenchers who were hoping to participate in the opposition day debate on the Grenfell Tower disaster.
"It was in that context and that context alone that having expressed my displeasure about the matter quite forcefully from the chair, I used the word 'stupid' in a muttered aside.
"That adjective simply summed up how I felt about the way that that day's business had been conducted.
"Anyone who knows the Leader of the House [Ms Leadsom] at all will have not the slightest doubt about her political ability and her personal character."
He insisted that he held all MPs in "the highest esteem" but indicated that he would continue to be critical of the Government from the speaker's chair.
Ms Leadsom spoke moments later, saying she expected all MPs to be treated with "courtesy and respect".
She said: "I take my responsibilities to this House very seriously. As you said last week Mr Speaker, we have a responsibility to safeguard the rights of this House."