Following the return of the original line-up Mutya, Keisha and Siobhan or MKS for short, Ewen has told Digital Spy that she can't see herself reuniting with Heidi Range and Amelle Berrabah to record new music.
The star - who has already been working hard on her solo material - told the website: "I don't even know if the band stuff is going to happen again, if I'm completely honest.
"I think Amelle wants to do her own solo stuff, Heidi is doing a Happy Days musical... I think we're pretty much done."
She continued: "I'm working on solo material at the moment actually. It's only come about in the past three weeks, so it's quite a new project.
"No-one's really seen me yet. I sang for Eurovision, I've been in a band, but I don't think anyone really knows what I'm about."
Ewen went on to add that she would love the current Sugababes to go on tour with MKS, claiming: "That would be awesome, it would sell out.
"That's easy for me to say though, I don't know how that would go down [with the other girls]. But I'm definitely up for it."
Earlier this week, MKS told BBC News that they are quite happy to leave the Sugababes name behind them, with Keisha explaining: "We could have had the name if we wanted to go get it I guess, but I don't feel like we needed it.
"There was so much emphasis on the name and we sort of wanted it to be about us."