Matt Hancock has been accused of "ludicrous rewriting of history" after he tried to claim it was wrong to say lockdown was imposed on a particular date.
The Health Secretary sowed fresh confusion by telling the Commons Science and Technology Committee that the government had "strengthened" restrictions from mid-March but the idea that lockdown "was a date" was incorrect.
The row began when Mr Hancock told MPs on Thursday that lockdown began on March 16 - the day he came to the House and said "all unnecessary social contact should cease".
In fact, Boris Johnson announced the UK was going into full lockdown on March 23 in a televised address where he told the public - "You must stay at home".
Schools had been closed to all but the children of key workers the previous week and the public were being advised to observe social distancing.
But enforcement measures were only brought in after the Prime Minister made his March 23 address.
Labour's Jonathan Ashworth said it was a "ludicrous rewriting of history from the Health Secretary who had previously told the Commons ‘lockdown began on 23 March".
Fresh confusion emerged when Mr Hancock was pressed on comments from the Chief Scientific Adviser Sir Patrick Vallance, who said SAGE experts had told ministers to begin implementing lockdown measures from March 16.
Mr Hancock told MPs: "It is absolutely true that we continued to strengthen the lockdown through this period.
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"The idea that lockdown was a date is wrong because actually what matters epidemiologically is the behaviour of people and you saw throughout this period people were going about their ordinary business less and less."
Labour MP Zarah Sultana challenged Mr Hancock on his claims.
She said: "I think it is very important that we address the issue of dates because what I fear is that you are taking part in historic revisionism and it is really important we have that sense of accountability.
"So do you stick by the fact that lockdown was on March 16 or lockdown was on March 23, or lockdown didn't happen, or it is not a date?"
Mr Hancock said a "whole series of actions were taken over that period" to tighten up restrictions.
He said the government had acted on the scientific advice from March 16 to limit social contacts among the public.
At the hearing, Mr Hancock said he believed that government had taken the "best decisions that we could, with the information that we had, at the time".
"People worked in the best possible interests of trying to tackle the pandemic," he said.