The Chief Executive of the DVLA has apologised for "misleading" MPs on the number of staff at their Swansea offices who have had coronavirus since September.
Julie Lennard was summoned before the Transport Committee after it was reported that there had been 535 cases of the virus at the south Wales base since September.
MPs accused her of "misleading" them by saying there had actually been a total of 546 cases since March, suggesting the total was spread across nine or ten months.
It later emerged that all but a handful of those positive cases had been identified from September onwards.
It comes as the Prime Minister said the UK Government is "working flat-out on the problem" with 2,000 Covid tests being carried out by the DVLA over the past fortnight.
The DVLA boss was put under pressure by MPs to address the large total number of Covid cases at their Swansea offices and claims from employees that coronavirus health and safety procedures are not being followed.
One employee told ITV News that staff are being told to "turn off" their track and trace and there is inadequate cleaning at the offices.
Ms Lennard denied those claims and said from the very start, "staff safety has always been, and remains, a priority".
She reiterated that there is currently no outbreak at their Swansea offices and insisted that a rise in case numbers during the end of 2020 reflected a "really big spike in the local community".
When asked to explain how many cases were contracted before September and how many after, it emerged that all bar 11 of the 546 cases had been contracted from September onwards.
Huw Merriman, Chair of the Transport Committee, said: "The way it was focussed to us in the letter, was that this big number should be spread across from March to now.
"But now you seem to be suggesting it could well be that the report of 535 cases from September is accurate, which is a very big number indeed."
He later added: "If I had a grand total of 546 and 535 of those were from September, I wouldn't write a letter and actually point it to my attention that it was a cumulative number stretching back from March - when March to September is a grand total of 11.
"I found it rather misleading."
Ms Lennard said she was sorry if she had misled the committee and admitted the DVLA could have been clearer in their presentation of the figures.
She said: "I can apologise if that was misleading, it is true, but I apologise.
"Obviously we were doing things at real speed because we had very little notice to attend.
"So I apologise if in the haste to actually pull a lot of the evidence together for you, some of those things could have been clearer."
At Prime Minister's Questions, Labour MP for Swansea East, Carolyn Harris, asked Boris Johnson if he would be taking "full responsibility" for "the woeful and reckless management of the Covid outbreak at the DVLA" in Swansea.
She added: "And will he also ensure that his Transport Secretary is held accountable for the inexcusable damage and devastation that this has caused?"
The Prime Minister responded: "We've been working flat-out on the problem at the DVLA and all staff who can work from home are doing so.
"Measures have been taken to minimise the number of people on the site at any one time and more than 2,000 tests have been carried out by the DVLA in the last fortnight alone, with all the results so far coming back negative."