A stability analysis is carried out for the m=1, n=1 internal kink mode, in the presence of energetic circulating particles. Including the effect of finite radial particle-orbit excursion, the energetic particles that cross the q<1 region can resonantly interact with the mode and destabilize it. For typical tokamak parameters, the growth rate of the instability is comparable to the one of the corresponding trapped-particle induced instability. Such an instability could explain the experimental observations of 'fishbone' oscillations during tangential neutral beam injection.