Mill claimed he would have taken RICO off his album if he'd found out earlier, and said he was speaking out because everyone else was "too scared to tell the truth".
"He don't write his own raps! That's why he ain't tweet my album because we found out!," he wrote.
In other rap battle news, Wu-Tang member Ghostface Killah released a video containing a tirade of abuse about fellow rapper Action Bronson, who is often referred to as having been influenced by Killah's rapping style.
In a YouTube video entitled 'Ghostface Killah air out Action Bronson,' Ghostface stalks around the room, muttering expletives and continually slamming Bronson.
"I'm too nasty for you," he says. "I don't want nobody to sound like me on no album ... Your fans? Those are my fans first.
He ends the video by threatening him. "I want you to enjoy your summer ... because you know a lot of people don't make it through the summer."
Bronson has apologised for the beef, apparently sparked by his comment that Ghostface "isn't rapping like this no more" on ESPN show SportsNation.
- nzherald.co.nz