LONDON (Reuters) - British Prime Minister Boris Johnson said on Thursday tempers needed to calm following a vitriolic session in parliament, after critics accused him of using language that had led to threats and abuse against his opponents.

Parliament reached boiling point on Wednesday when Johnson and his opponents engaged in hours of furious argument over Britain’s departure from the European Union. Lawmakers hurled allegations of betrayal and abuse of power across the chamber.

The anger had become so intense that the husband of a lawmaker murdered days before the 2016 EU membership referendum said it could encourage violence unless politicians toned down their rhetoric.

“We do need to bring people together and get this thing done,” Johnson told BBC TV, declining to apologize for his language. “Tempers need to calm down and people need to come together because it is only by getting Brexit done that you will actually lance the boil of the current anxiety.”

The ferocity of the Brexit debate has shocked allies of a country that has prided itself on being a confident - and mostly tolerant - pillar of Western economic and political stability.

However, three years since Britons voted to leave the European Union, the outcome remains mired in uncertainty with supporters on both sides of the debate becoming increasingly entrenched.

UNLAWFUL

Johnson returned to the House of Commons on Wednesday after the Supreme Court ruled that his decision to suspend parliament earlier this month was unlawful.

He challenged his opponents either to bring down the government or get out of the way to allow him to deliver Brexit, something he has vowed to do by Oct. 31 whether or not he has agreed a withdrawal deal with the European Union.

His opponents roared “resign” and some cast him as a cheating dictator who should stand aside after the court ruling.

Johnson provoked anger by repeatedly calling a law that forces him to ask the EU for a three-month Brexit delay next month unless he can strike a deal as the “Surrender Bill”.

His critics say such language is often used in threats of violence or worse received by lawmakers, particularly women.

A far-right extremist was jailed in May for planning to murder a female lawmaker with a sword, while on Thursday a lawmaker from the opposition Labour Party said a man had been arrested at her office for striking the windows and shouting “fascist”.

“The prime minister’s language is encouraging people to behave in a disgraceful and abusive way towards other public figures,” said Jeremy Corbyn, the Labour leader. “I have witnessed it myself on the streets of this country.”

Johnson defended his use of “surrender bill”, arguing that the legislation hurt Britain’s negotiating stance with the EU.

“I think it’s fair enough to call the surrender act what it is,” he told the BBC. He said the growing threat to lawmakers had to be addressed but declined to apologize for his words and disputed suggestions his language was stoking feelings.

“What I worry about is if we don’t get Brexit done, then people will feel very badly let down,” he said.

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However, he acknowledged that the toxic atmosphere meant opposition lawmakers might not support any Brexit deal he struck with the EU, making it almost impossible to get it through parliament, where he has no majority.

Many politicians were furious over his response on Wednesday to a question about Jo Cox, a 41-year-old Labour lawmaker and mother of two children who was murdered on June 16, 2016 by a loner obsessed with Nazis and extreme right-wing ideology.

When one female Labour lawmaker said she had had threats from people echoing the prime minister’s rhetoric, Johnson replied: “I have never heard so much humbug in my life”

Cox’s husband Brendan said both sides should ponder the impact of the words they used.

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“To descend into this bear pit of polarization is dangerous for our country,” Cox told the BBC. “It creates an atmosphere where violence and attacks are more likely.”

PM’S SISTER UNIMPRESSED

Johnson says parliament is betraying the will of the people over Brexit, while opponents cast him a dictator who has ridden roughshod over democracy to take the United Kingdom to the brink of ruin.

Parliament speaker John Bercow said the atmosphere in the House of Commons was the worst he had known since he was elected 22 years ago.

It was not just politicians who were angry. Johnson’s sister Rachel described her brother’s words as a “particularly tasteless” way to refer to the memory of a murdered lawmaker.

“Words like collaborationist, traitor, betrayal, my brother using words like surrender, capitulation, as if the people who are standing in the way of the blessed will of the people as defined by 17.4 million votes in 2016 should be hung, drawn, quartered, tarred and feathered,” she told Sky News.

“I think that it is highly reprehensible language to use.”

In 2016, 17.4 million voters, or 52 percent, backed Brexit while 16.1 million, or 48 percent, voted to remain.

Former Conservative prime minister John Major, a vocal critic of Johnson, said he hoped many of his party’s supporters would see the current government as an “aberration”.

“We abhor the language of division and hate – and words such as ‘saboteur’, ‘traitor’, ‘enemy’, ‘surrender’, ‘betrayal’ have no place in our party, our politics, nor in our society,” he said.