Labour leader Jeremy Corbyn warned that the words politicians use "have real consequences" as he condemned the Prime Minister's language in the Commons.
"The Prime Minister's language and demeanour yesterday was frankly nothing short of disgraceful.
"Three years ago our colleague, our member, Jo Cox, was murdered by a far-right activist shouting 'Britain First, this is for Britain'. The language that politicians use matters and has real consequences.
"To dismiss concerns from members about the death threats they receive and to dismiss concerns that the language by the Prime Minister is being repeated in those death threats is reprehensible.
Mr Corbyn said he has written to his own MPs to set out the standard of behaviour he expects from them.