On the TQFT representations of the mapping class groups

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 g greater than or equal to 2 and the level of the theory r not equal = 2, 3, 4, 6 (and r not equal 10 for g = 2). In particular it follows that the quotient groups M(g)/N(t(r)) by the normalizer of the r-th power of a Dehn twist t are infinite if g greater than or equal to 3 and r not equal 2; 3; 4; 6; 8; 12.