The Ant and Dec star was fined £86,000 and banned from driving for 20 months after he pleaded guilty to drink driving at the hearing at Wimbledon Magistrates’ Court.
During a discussion about the TV presenter’s court case on Tuesday’s ‘Good Morning Britain’, Piers said: “He does not deserve sympathy.”
The journalist then revealed: “I have partied with him in the past.”
Piers, who worked with Ant when he was a judge on ‘Britain’s Got Talent’, added that the 42-year-old star looked “haunted” as he faced the media scrum outside the court.
It’s not the first time Piers has spoken out against Ant.
Last month the journalist claimed Ant was “not the guy he knows”.
Following the news Ant had pulled out of all TV commitments to return to rehab after he crashed his car into two other vehicles in south London, Piers said: “He’s definitely changed, no question.”
“I’ve known Ant a long time and I like him very much, but I wonder if he’s getting a little bit too much of arm round, ‘are you OK, mate?’ and not enough, ‘mate, what are you doing?’,” he said.
“If I had the chance to speak to him, which I won’t now, I would say that to him. As a friend, you are throwing away your career here. You can’t afford too many more days with headlines like this.”
“This Ant McPartlin is not the guy I know. His life is faltering and tormented for some reason. I’d like to see him off TV for a long time as he came back too soon [after rehab].”
Piers went on to express his sympathy for Ant’s co-presenter Declan Donnelly, claiming he has become “collateral damage” in the situation.
“I feel for Dec, by default, his career reaches the buffer as they’re a double act,” he said. It’s incredibly difficult moment for him. In the television world this is an earthquake.”
He continued: “It’s Dec I feel sorry for more than Ant because Ant is in control of his own behaviour and is making bad choices. Dec is the collateral damage.”
After Monday’s hearing, Ant told reporters outside court he is “truly sorry for what happened”.
“Higher standards are expected of me. I let myself down, I let a lot of people down, for that I’m truly sorry,” he said.
“I’d like to apologise to everyone involved in the crash and I’m just thankful no-one was seriously hurt.”