The `Bodies` hitmaker - who left the group in 1995 and embarked on a successful solo career - has revealed he has been meeting up with former bandmates Gary Barlow, Howard Donald, Jason Orange and Mark Owen to work on a secret project.
When asked if he`ll be performing with the foursome again, he said: "We`ve got together, done bits and bobs. I can`t say much, but yes, I hope so."
The 35-year-old singer - who has previously battled alcohol and drug addictions - also spoke candidly about how he was forced to stop performing in 2007 when his personal problems began to spiral out of control.
In an episode of TV talk show `Friday Night With Jonathan Ross` due to air in the UK on Friday (06.11.09), he said: "The decision to quit playing live was made for me, I`ve always been very nervous... 80,000 people, it`s an unnatural thing to do. You don`t know what`s going on in my head.
"It`s traumatic, really scary. I ended up in rehab again, it was `What are you doing to yourself?` I thought it`s time to break the cycle."
Robbie is now determined to remain sober for his girlfriend of three years, Ayda Field, so they can start a family together.
He added: "I`ve taken the pressure off myself, it`s a part-time thing these days. The missus keeps me grounded. There`s no need to take myself out of my mind any more.
"I thought I was going to be a bachelor but I was introduced to Ayda and things just changed. She`s a wonderful person and I`m in love. She`s really broody and I`m getting there."
Robbie sparked speculation he was working with the group again after they were all spotted at New York`s Electric Lady Studio while the band were in America for Mark?s bachelor party.