Cheryl is said to be "angry" over Nadine Coyle speaking out about Girls Aloud's split.
Earlier this month Nadine spilled all, claiming she had no say in the group's decision.
The girl group were formed on Popstars The Rivals back in 2002 and were one of the first - and even to this date, very few - success stories from such reality talent shows.
They parted ways in 2013 following a Greatest Hits tour but Nadine says it wasn't her choice.
Nadine alleged she found out just before the groups' final performance.
“I thought we were going to continue. I thought we were going to do loads and loads of stuff," Nadine explained. "We had songs, we had a three-album deal and it seemed like a great time. Obviously the girls had different plans.
“The very last night, management had come to the room.
"I was all ready, just about to get dressed and they were like, ‘So I know you’re not going to like this, I know you’re not going to agree, but the girls want to split up the band’."
Nadine, who recently returned with new solo single Go To Work, said there had always been a split in the band with herself and Sarah Harding on one side and Cheryl, Kimberley Walsh and Nicola Roberts on the other.
She told The Sun newspaper: "It’s so sad for me to have to admit this stuff now because for so long, there’s the band, and you want everybody to think we’re best friends and we have pillow fights and, you know, drink milkshakes.
“That’s what I wanted it to be. I really, really wanted that to be, but it just wasn’t how it was."
Nadine's bandmate Cheryl is reportedly unhappy with the comments that come ahead of the group's fifteenth anniversary.
A pal told Closer magazine: "She wishes they could just leave it and enjoy the success they had as a band."
And a source added: "She plans to keep a dignified silence, but worries Nadine is determined to stir up ill feeling."
Back in 2014, Cheryl branded Nadine "full of s**t" after the group's split got messy.
"She was the one who wanted to make a solo record. Which is why we took the hiatus," Cheryl told Attitude magazine. "She wants to come out and say we broke the band up? No! She shouldn’t tell porkie pies."
We're guessing any potential reunion is off the cards...