Kasabian say former frontman Tom Meighan misled fans by choosing not to talk about his assault charge.
Meighan admitted one count of assault by beating at Leicester Magistrates’ Court on Tuesday morning and was sentenced to 200 hours of unpaid work.
The court heard he pushed his ex-fiancee, Vikki Ager, into a hamster cage and threatened her with a wooden pallet in front of a child in April last year.
In a statement to fans, the band say they are “completely heartbroken” by the departure of Meighan, but added they were left with no choice but to ask him to leave.
“There is no way we can condone his assault conviction. Domestic violence and abuse of any kind is totally unacceptable,” they said.
“As soon as we found out about the charges made against Tom, we as a band made the decision that we could no longer work with him.
“We were led to believe that Tom would hold his hands up and in his statement tell everyone what he’d done but he chose not to, misleading a lot of fans.”
The band continued: “Ultimately, as much as Tom has hurt us all, we’re not the victim in all of this. Domestic violence is something that can never be excused.”
Kasabian said that they had waited until after the court case had ended before commenting.
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Leicester Magistrates’ Court was told on Tuesday that Meighan “smelt heavily of intoxicants” as he assaulted his former fiancee, and that a child witnessed the attack before calling 999 to say a “domestic incident was taking place”.
Prosecuting, Naeem Valli said the child “sounded panicked and afraid” while making the call and the victim could be heard saying “get off me, get off me”.
He added that police officers described Ms Ager as “visibly upset”, while Meighan was “uncooperative and aggressive”.
Meighan, of Narborough in Leicestershire, originally denied the assault had taken place but after watching video footage, he told officers he could not watch any more because it was “horrible”.
As the CCTV footage was played in court, Meighan wiped his eyes with a tissue and held his head in his hands.
Ms Ager suffered bruising to her knees, left elbow, outer ankle and big toe as well as a reddening around the neck, the court was told.
District Judge Nick Watson, sentencing Meighan, told the singer: “Ms Ager has not made a statement to police and does not appear to support this prosecution.
“Of course, that choice does not mean I should treat this offence any less seriously.
“You knocked Ms Ager over on more than one occasion and put your hands to her throat.”
The judge added that as well as hurting Ms Ager, Meighan let down his band members and fans, and said he has “a problem with alcohol”.
“They will be shocked about what you did that night,” Mr Watson said.
Meighan’s departure from Kasabian leaves guitarist Serge Pizzorno and bass player Chris Edwards as the only remaining founding members, with current drummer Ian Matthews joining the group in 2004.
It is not clear whether the band will look to replace Meighan as lead vocalist.