A week after walking out of Conor McGregor’s training camp, his former sparring partner has launched into another attack on the Irishman.

Paulie Malignaggi was helping McGregor to prepare for his fight with former boxing world champion Floyd Mayweather on 26 August. However, he was unhappy that McGregor’s camp released photos that showed the UFC champion getting the better of him in the ring, and called the build-up to the fight a “fiasco”.

In an interview with the MMA Hour, Malignaggi resumed his attack. “This guy is one of the biggest dirtbags I’ve ever met in my life – bar none,” said Malignaggi, a former boxing world champion. “I was amazed at what a dirtbag this person is. I don’t care if we never speak again. My life is fine if I never see Conor McGregor again.

“I was dumbfounded by the way things were. It’s just about status with him. It makes me doubt if he ever really went through a tough time in his life like they try to say he did. If somebody went through that tough a time in life just a few years ago, they wouldn’t treat people who were not as fortunate as him that bad.”

Malignaggi had been particularly incensed at photos that appeared to show McGregor knocking him down in the ring. The boxer insists he was pushed, and says McGregor is scared to be challenged.

“He doesn’t want to be put in those positions. He wants to be the front runner,” Malignaggi said. “He wants to be the guy who always has the advantage, because when he has an advantage he’s a big man. When he gets tired, he wants out of a fight.”

McGregor and Mayweather will make tens of millions of dollars out of the fight but Malignaggi says he was afforded few privileges as a sparring partner. “[My accommodation was] in a dilapidated neighborhood. It’s a rundown house,” Malignaggi said. “I mean, yeah, it works. But it’s not really what you expect. … It reminded me of some kind of crack house that had been barely renovated a little bit.”

The run-up to the Mayweather-McGregor fight has been far from smooth, and at times has struggled to rise from schoolyard level. McGregor called Mayweather, who is African American, “boy” in their first press conference, a comment widely seen as racially insensitive, including by Mayweather himself. The American went on to call McGregor “a faggot”. Tickets for the fight at Las Vegas’s T-Mobile Arena, which cost up to $15,000, have also sold slowly.