Senior Metropolitan police officer John Yates has insisted he did not mislead the Commons' culture, media and sport committee over phone-hacking.
The acting deputy commissioner said he was able to offer an "absolute rebuttal" of Labour MP Chris Bryant's allegations in a Commons debate last week.
Mr Bryant had suggested Mr Yates had misled the committee by claiming that there were only up to 12 victims of phone-hacking at the News of the World, during the investigation which eventually led to the conviction of Glenn Mulcaire and Clive Goodman.
Crown Prosecution Service advice at the time was that proving the offence of voicemail interception meant demonstrating that a voicemail had been intercepted prior to it being listened to by the intended recipient, Mr Yates said.
"The fact remains that during the Mulcaire and Goodman case and throughout the ensuring period until October 2010 the legal advice on this matter was unequivocal," he told MPs.
"The significance of this point is very clear. I've always cautioned... that while suspects may have targeted many people as private investigators, we could only actually prove the offence of voicemail interception in a small number of cases."
Mr Bryant was among those whose phones were interfered with, in an ongoing scandal which cost former No 10 communications chief Andy Coulson his job.
He has continued to press the issue but now faces a firm rebuttal from Mr Yates, who when confronted with his clash with Mr Bryant by one MP simply replied: "Whatever."
"I'm very clear that Chris Bryant was wrong," he added later in the evidence session.
"I think I've got a very clear factual audit trail that I think supports that view."
A fresh investigation probing phone-hacking was triggered after a massive media furore over the issue last year. Mr Yates conceded that the Met had not done enough to pursue the scandal.
"The experience would suggest that perhaps more in the last three years more could have been done," he admitted.
"But we have a new investigation, I think we should allow them to get on with it."