Gardaí made up 1.5 million fake breath tests between 2009 and 2016.
An investigation has discovered an extra 500,000 false tests and found some gardaí were exaggerating figures by 300%.
The Justice Minister has received the reports and is due to brief the cabinet on them this morning.
Tánaiste Frances Fitzgerald, who was justice minister when the false figures were first discovered, said it's deeply disturbing.
"The information that came out last year about the breath tests and the other issue clearly was unacceptable.
"I understand we now have the reports - Minister Flanagan has them - I haven't seen them yet so I'll wait until Cabinet to hear what is actually in those reports.
"But of course the suggestion that you make up an additional 500,000 would be deeply disturbing".