Robbie Williams and the boys will release the eight tunes as part of a double disc album titled Progressed.
An insider told British Metro newspaper: 'The creative process was better than ever with Robbie back on board, so they just kept churning out ideas.
'They decided the tracks were just too good to let disappear into nothing, so they have finished them off in between rehearsing for the tour and are pretty happy with the results. It's their extra gift to loyal fans.'
The new tracks include current single Love Love, which is also featured on the soundtrack to the film, X-Men: First Class.
Progressed is due to be released on June 13.