Boris Johnson has refused to moderate his language during a heated debate in the Commons, despite a barrage of criticism from opposition benches.
Labour’s Paula Sherriff referred to Jo Cox, the MP murdered in 2016, as she pleaded with him to refrain from using “dangerous” words like “surrender”.
He described her intervention as “humbug” and repeated the word again.
The SNP’s Nicola Sturgeon said there was “a gaping moral vacuum where the office of prime minister used to be”.
BBC political editor Laura Kuenssberg described scenes in Parliament as an “absolute bear pit”.
Mr Johnson was repeatedly challenged over his use of the word “surrender” to describe legislation passed earlier this month which aims to block a no-deal Brexit on 31 October.
Ms Sherriff, the Labour MP for Dewsbury, told the Commons the prime minister had “continually used pejorative language to describe an Act of Parliament passed by this House”.
Pointing to a plaque in the chamber, commemorating Mrs Cox, who was murdered by a right-wing extremist, she said: “We should not resort to using offensive, dangerous or inflammatory language for legislation that we do not like, and we stand here under the shield of our departed friend with many of us in this place subject to death threats and abuse every single day.”
“They often quote his words ‘Surrender Act’, ‘betrayal’, ‘traitor’ and I for one am sick of it.
“We must moderate our language, and it has to come from the prime minister first.”
In response, Mr Johnson said: “I have to say, Mr Speaker, I’ve never heard such humbug in all my life.”
Tracy Brabin, who was elected as MP for Batley and Spen after Ms Cox was murdered, also urged the prime minister to moderate his language “so that we will all feel secure when we’re going about our jobs”.
Mr Johnson replied that “the best way to honour the memory of Jo Cox and indeed the best way to bring this country together would be, I think, to get Brexit done”.