The pop group confessed that Ian 'H' Watkins's friendship with the US superstar while they supported her North American tour caused tension in the band.
Revealing all in their Sky Living series Steps Reunion, the 'Tragedy' performers admitted that problems first arose when H started flying in Spears's private jet while the rest of them travelled by bus.
The Sun quotes Lisa Scott-Lee as saying: "It got people's backs up."
Further cracks apparently appeared when Claire Richards discovered that H had been secretly dating the band's manager Tim Byrne.
Steps Reunion starts tonight on Sky Living at 9pm.
> Steps unveil 'The Ultimate Collection' album
Watch Digital Spy's exclusive interview with Steps below: