The Labour MP Dawn Butler has been ejected from the Commons after saying Boris Johnson had lied repeatedly to fellow parliamentarians and the country, and then refusing to withdraw the remark.

“The prime minister has lied to this house time and time again,” Butler told the deputy speaker, Judith Cummins. When asked to “reflect on her words”, Butler added: “It’s funny that we get in trouble in this place for calling out the lie, rather than the person lying.”

Under Commons rules about what is considered unparliamentary language, it is forbidden for MPs to accuse their fellows of deliberate deceit.

Speaking in a backbench business debate shortly before the end of the final day of Commons business before the summer recess, Butler condemned the government’s response to coronavirus.

“Poor people in this country have paid with their lives because the prime minister spent the last 18 months misleading this house and the country,” the Brent Central MP said.

Butler cited a much-shared social media video collating many of Johnson’s incorrect statements, highlighting in particular the prime minister’s comment to MPs earlier in the month that the Covid vaccination programme had “severed” the link between infections and serious illness or death.

While this appeared an error rather than a deliberate attempt to deceive – the official government line remains that the link has only been weakened, not severed – Johnson has never corrected himself, and fellow ministers have refused to accept he was wrong.

Butler told MPs: “Not only is this not true, it’s dangerous. It’s dangerous to lie in the pandemic. And I’m disappointed the prime minister has not come to the house to correct the record, and to correct the fact that he has lied to this house and the country over and over again.”

At this point Cummins, a fellow Labour MP who is a stand-in deputy speaker after one of the office holders, Rosie Winterton, was forced to self-isolate, intervened to twice ask Butler to withdraw the charge of lying.

Butler said: “I’ve reflected on my words, and somebody needs to tell the truth in this house, that the prime minister has lied.” Cummins told the MP she was suspended for the rest of the day, and Butler left the Commons.

Johnson’s tendency towards dishonesty is much chronicled, with a series of people who have known him commenting on what Max Hastings, his editor at the Daily Telegraph, called “his moral bankruptcy, rooted in a contempt for truth”.

Under his tenure as prime minister, Downing Street has often declined to correct the record when he has said something false, even on issues that are not in doubt.

However, in a chamber where MPs must refer to each other as the “honourable member”, accusations of dishonesty are forbidden. An official glossary of other unparliamentary language not permitted by Speakers in recent years includes “blackguard”, “coward”, “git”, “guttersnipe”, “hooligan”, “rat” and “stool pigeon”.