Ms Rayner became embroiled in a war of words with Chancellor of the Duchy of Lancaster, Kit Malthouse, in the Commons.
The 42-year-old accused Mr Malthouse of spouting “sexist nonsense” in response to concerns of a “cover-up” over the Covid public inquiry.
In return, Mr Malthouse called the Labour frontbencher "toxic" and suggested she was asking questions comparable to: "When did you stop beating your wife?"
Responding as opposition MPs heckled Mr Malthouse, Sir Keir Starmer's second-in-command said: “It’s not a phrase I would use.
"It’s not one I’d advise any Government minister using.
Labour deputy leader Angela Rayner in the House of Commons
House of Commons
“The Government has serious questions to answer about the independence of the long-delayed Covid inquiry – I’d expect the minister to provide me with a serious answer, not spout some old-fashioned, sexist nonsense.
“The toxic legacy of Boris Johnson is the debasing of standards in public life and Conservative MPs have been entirely complicit.”
Speaking in the Commons earlier, Ms Rayner acknowledged the country had reached the “dark milestone” of more than 200,000 Covid-19 deaths.
She told Mr Malthouse: “The Prime Minister delayed the start of the public inquiry into the Government’s handling of the pandemic, with the hearings not expected until 2023, making a full inquiry unlikely before the next election.”
Chancellor of the Duchy of Lancaster Kit Malthouse
Victoria Jones
Ms Rayner highlighted reports suggesting the Government was “trying to block evidence to the inquiry, with ministers fearful they could be sued for damages”, adding: “There can be no hint of a cover-up or excuses for ministers dodging scrutiny.
“Does he deny those reports that have been in the press and, if not, how can he assure us and the public that process will be independent?”
Mr Malthouse replied: “Well, the honourable lady has her very own brand of toxic which she attempts to pump into everything the Government does and she’s effectively, no, no, no, no, we literally can’t conduct debate in this House on the ‘when did you stop beating your wife’ questions.
“This inquiry will be one that will be independently chaired and thoroughly conducted. It will have statutory powers to summon evidence and witnesses in the way that others have done.”
Mr Malthouse said the Government was “determined to learn the lessons of the Covid pandemic”, adding: “Nobody thinks that everything that happened during the pandemic was perfect.
“But to start her contemplation of this issue by maligning the motives of those ministers who put their shoulder to the wheel at a time of national emergency is frankly disgraceful.”
Mr Malthouse earlier told MPs “I own a young man in his 20s” – before acknowledging it was his son.
Conservative MP Lee Anderson (Ashfield) pressed the minister to ensure civil servants were back in the office.
Mr Malthouse replied: “We do want to see as many people as possible back in the office, not just because it’s more efficient, not just because we think it’s a better way for government to operate, but also because we all, importantly, have a duty to the young.
“It is impossible for the young to acquire the skills and the abilities that they need when they are working remotely.
“As somebody who has someone in their 20s, well, I own a young man in his 20s, my son, I know how debilitating it would be for those who are starting their career to operate from their bedrooms.
“Those of us in senior positions have a moral duty to be present in person with them to give them the skills and abilities they need to advance their careers.”
Cabinet Office colleague Jacob Rees-Mogg also appeared to blame civil servants working from home for delays in public services for items such as driving licences and passports, saying technology was “unquestionably the answer” to reduce delays.
Mr Rees-Mogg said: “What is going on is that too many people are still working from home. We need to get people back in the office doing their jobs. But we can also do more with fewer people.”