Liam Gallagher claims his brother Noel's "lies" are breaking his heart.
The ex-Oasis frontman is upset he has been blamed for the band's demise by the guitarist, denying the reasons for their split began with him being too hungover to perform at England's V Festival in Chelmsford in August 2009.
Speaking to the UK's BBC Radio 1, Liam said: "Those are big lies that I've got to clear up, the first one about me being hungover - I got diagnosed with laryngitis for the V festival, wasn't hungover. I do gigs when I've been hungover, I'm a Big Boy.
"I'm not going to cancel a gig because I've got a headache."
The singer - who now fronts Beady Eye - also dismissed the idea they fell out over advertising his Pretty Green clothing label in an Oasis tour programme.
He added: "Them words, Pretty Green, have never come out of my mouth [to] Noel Gallagher. Ever.
"So all this about him saying I tried to get Pretty Green in an advertisement or Oasis tour programme is absolute s**t, saying it's the demise of Oasis, I'm not having it.
"He needs to know there's to blame for Oasis splitting up and one of them is sitting here right now talking, and the other one's noel Gallagher. It's time he woke up man, he's no angel.
"He's breaking my heart."
Liam, 38, has even said he would be prepared to fight his brother "verbally, physically, musically and mentally" over his claims and following the announcement of his debut solo album, `Noel Gallagher's High Flying Birds', last week.
He added: "I don't play games. Competition is for idiots. As long as we are taking care of our business, we'll roast anyone.
"I'm quite prepared to go head to toe verbally, physically, musically, mentally with Noel Gallagher. We've heard our new tunes and they're big, so bring it on."
Since the end of Oasis, Liam formed Beady Eye with the other remaining members of Oasis - Gem Archer, Andy Bell and Chris Sharrock.
Beady Eye - which includes ex-Oasis members Gem Archer, Andy Bell and Chris Sharrock - are currently on a European tour, while `Noel Gallagher's High Flying Birds' will be released on October.