Boy George has described the singer who has replaced him in pop band Culture Club as "terrible" and "dreadful".
Boy George exhibited his clothing range at London Fashion Week
The 45-year-old star led the group to global stardom with hits such as Karma Chameleon and Do You Really Want To Hurt Me in the 1980s.
The band recently recruited newcomer Sam Butcher for a UK tour in December.
Boy George said he had seen their video on MySpace. "I wanted to like it but I couldn't," he said. "They're my songs, they're my heart, they're my life."
Original band members Jon Moss, Mikey Craig and Phil Pickett recruited 29-year-old Butcher through auditions this summer, after Boy George decided not to go back on tour.
They have described their new frontman as "angelic and willowy" and "an intriguing and attractively unique individual".
Butcher was unveiled to media and fans at an intimate gig in London in July, where his colourful style and androgynous image echoed the persona of his predecessor.
Boy George added: "They're my gay love songs about my boyfriend. He can't sing them, can he?
"To me, the mark of a good band is when someone else can't successfully sing their songs, and he can't sing my songs."
Culture Club said they wanted Boy George to sing with the band again but he refused, and that they did not want to be involved in sniping.
Butcher said: "I wish George well with his new solo career. I am hurt by George's comments but realises George says terrible things about everybody, including Madonna.
"I am just starting my career so it seems rather cruel to take pot shots at me. Maybe Boy George should keep it for the big boys like Madonna and George Michael."
Boy George made his comments at the Vodafone Live Music Awards on Wednesday, where he also had a confrontation with several youths who were shouting abuse.
The singer marched up to the onlookers, who were taunting him through a door at the Camden Roundhouse venue, telling them he would "knock your teeth out" and calling them "chavs".
Boy George - fresh from sweeping streets in New York as part of community service - recently exhibited his clothing range at London Fashion Week.
He is also releasing a single, Time Machine, with Amanda Ghost, who co-wrote James Blunt's hit You're Beautiful.
Culture Club's 12-date UK tour starts in Manchester on 7 December.