The heated exchange began with Dan's tweet about an interview he conducted with RMT union boss Mick Lynch on 5 News.
WATCH: Dan Walker bids heartfelt goodbye to BBC Breakfast
Tweeting a clip of his chat with Mick, Dan wrote in the caption: "We live in the age of the jabby, confrontational interview & the RMTs, Mick Lynch, has had a few of them.
"If you treat people with respect, you can still ask tough questions & get decent answers allowing your audience to make their own minds up @5_News."
The former GMB presenter was quick to respond to Dan's post with laughing emojis alongside the caption: "Is there anyone more deluded in world television than Desperate Dan.. the world's most boring interviewer."
Upon seeing the tweet, Dan replied: "Why is it 'boring' to let someone actually speak rather than shouting over them all the time?" alongside laughing emojis.
Dan recently moved from the BBC to Channel 5
The tense dialogue didn't end there as Piers came back at Dan, writing: "Mate, I had to leave GMB for being too exciting/dangerous.
"You had to leave the BBC because even by their standards you're a mood-hoovering dullard. But your pompous lectures on how to do interviews are [expletive] funny, I'll give you that."
Dan was quick to reply with a gif of Piers storming out of Good Morning Britain, which happened back in March last year. He wrote the caption: "You left GMB because one of your colleagues called you out.
"Your 'exciting/dangerous' response to that was [finger emoji pointing to the gif].
"Next time I promise to spend at least five minutes on Thunderbirds."
Piers left the ITV breakfast show last year
The two former daytime presenters have shared a rivalry over recent years and the series of tweets comes after Dan spoke out about Piers' presenting style in a recent interview with The Sunday Times.
He told the publication: "You can only be authentic to who you are but I don’t want to portray a persona like Piers," he said. "And I've never dipped to his level of insults.
"I think he overstepped the mark when he smashed a mug with my face on it. I don't need to do that sort of thing," he added, referring to a moment in 2017 when Piers smashed a cup that had the BBC Breakfast logo on it live on air; Dan's face was actually not on the mug.
He continued: "When I first started at BBC Breakfast I met him at a function and he said, 'You're going to be terrible. We're going to annihilate you.' But my attitude was to remain quietly confident," before going on to reveal the comments he made to Piers following his GMB departure. "I told him, 'All those years you were on GMB you mentioned me almost every day and we didn’t mention your name once until the day you left.'
"I think there is room for both styles of broadcasting but Piers? That's not a persona I could inhabit because I would feel very fake," he added.
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