Former Oasis frontman Liam Gallagher is suing his brother Noel over his claims the band once cancelled a gig because the singer was hungover.
Noel Gallagher told journalists at a press conference in July that it was the real reason why the band pulled out of the V Festival in 2009.
The official explanation at the time was that Liam Gallagher had laryngitis.
In a statement, he said he had "tried to resolve this amicably but have been left with no choice but legal action".
"All I want is an apology," he added.
The brothers have had a long-running public spat since they found fame in the mid-1990s.
However Liam, 38, said his brother's comments "went way beyond rock-and-roll banter and questioned my professionalism".
Noel, 44, made the claims as he promoted his debut solo album Noel Gallagher's High Flying Birds.
Explaining the demise of the band, he cited the V Festival incident as a contributing factor and further claimed his younger brother demanded free advertising space for his clothing label, Pretty Green, in the band's tour programme.
However Liam branded the claims "lies".
"I want Oasis fans, and others who were at V, to know the truth," he said.
"I was gutted when I couldn't play the gig because I didn't want to let the fans down. The truth is I had laryngitis, which Noel was made fully aware of that morning, diagnosed by a doctor."
He also disputed suggestions of an argument over his clothing line, saying "there was no such discussion or row".
The band split up soon after. Liam now fronts Beady Eye, made up of former Oasis band members.
Representatives for Noel have not commented on the action.