  We prove that the image of the mapping class group by the representations
arising in the SU(2)-TQFT is infinite, provided that the genus is bigger than 2
and the level r of the theory is different from 2,3,4,6. In particular the
quotient of the mapping class group by the normaizer of the r-th power of a
Dehn twist is infinite if the genus is at least 3 and r is bigger than 12.
