Former Pussycat Doll -- Nicole Scherzinger Was a Huge Diva

Former Pussycat Doll Kaya Jones is firing back at Nicole Scherzinger's recent diss towards the rest of her PCD bandmates ... claiming Nicole only sang most of PCD's songs because she REFUSED to share the spotlight.

Scherzinger made headlines this week, when a clip of her upcoming VH1 "Behind the Music" special revealed her true feelings about the girl group -- specifically Nicole claims to have sang 95% of PCD's songs on their first album (below).

TMZ spoke to former Pussycat Doll Kaya Jones -- who does NOT out right deny the claim -- but is adamant ... the only reason Nicole sang lead vocals for everything, is because "there was a lot more going on behind the scenes."

Kaya -- who starred in the group from 2003-06 with Nicole -- says, "Nicole was always someone who wanted to be in the spotlight and would do pretty much anything to get it."

She adds, "To call the other girls in the Pussycat Dolls 'window dressings' is a bit farfetched ... every girl in the group was talented."