Their number ones include Freak Like Me and Push The Button
Former Sugababe Keisha Buchanan has claimed that it was not her decision to leave the successful pop group.
Founding member Buchanan has quit to focus on her solo career after 11 years with the trio, according to the band's official website.
It comes after media reports speculated on a rift with bandmate Amelle Berrabah, who missed a performance earlier this month.
Buchanan, 24, cited "a breakdown in communication" and "lack of trust".
Writing on social networking site Twitter, Buchanan said: "Although it was not my choice to leave, it's time to enter a new chapter in my life, I've had a great time and have achieved more then I ever thought I would."
Berrabah will stay on with existing member Heidi Range and newcomer, this year's UK Eurovision entrant Jade Ewen.
Buchanan added: "Sometimes a breakdown in communication and lack of trust can result in many different things. I would like to state that there were no arguments, bullying or anything of the sort that lead to this.
"I have nothing but positive things to say about the girls and I wish them the best of luck."
Berrabah recently enjoyed a UK number one single Never Leave You, with urban artist Tinchy Stryder.
Buchanan wrote: "Remember my drunk pictures out with Amelle, supporting her on her success with Tinchy Stryder... Oh the shame...
"But what a fun night we had, I would also like to point out that I have always supported the girls and they have also supported me."
Later in the message, she describes herself as "the feisty, funny, professional, fearless, motormouth".
Jade Ewen came fifth at this year's Eurovision
The statement on the band's website said of the split: "The current line-up of the Sugababes has disbanded.
"Heidi Range and Amelle Berrabah will continue as the Sugababes and will be joined by new member Jade Ewen."
It added that their album Sweet 7 would be released on 23 November through Island Records, and that Buchanan would continue to record for the company as a solo artist.
The group was formed in 1998 by Buchanan, Mutya Buena and Siobhan Donaghy.
Heidi Range replaced Donaghy in 2001 and in 2005 Buena was replaced by Berrabah.
The Sugababes have enjoyed six UK number one singles, including Freak Like Me and Push the Button.
But the last 12 months have seen them release the lowest-selling album of their career.
Speaking to BBC 1Xtra about the latest line-up change, Buena said: "It doesn't make sense that there is a Sugababes any more."
"Not having any of the original members in it, it will be more [about] the brand name Sugababes than it will be the singers."
She also cast doubt on Ewen's ability to fit into the line-up.
"I reckon she would be a lot better as a soloist because she's got an amazing voice," she said.
"So it will kind of seem like she would be in the front line and there will be two backing singers."
HOW SUGABABES LINE-UPS HAVE FARED
Sugababes releases during each line-up (highest chart position in brackets):
1998-2001: Buchanan, Buena & Donaghy
New Year (12)
Run For Cover (13)
Soul Sound (30)
One Touch (36)
2001-2005: Buchanan, Buena & Range
Freak Like Me (1)
Round Round (1)
Hole In The Head (1)
Too Lost In You (10)
In The Middle (8)
Caught In A Moment (8)
Push The Button (1)
Angels With Dirty Faces (2)
Taller In More Ways (1)
2005-2009: Berrabah, Buchanan & Range
Red Dress (4)
Follow Me Home (32)
About You Now (1)
No Can Do (23)
Get Sexy (2)
Overloaded (singles collection, 3)
Catfights And Spotlights (8)