We present heretofore unreported Viking observations of sporadic AKR bursts occurring well above the electron gyrofrequency together with spiky electrostatic emissions recorded just above the lower hybrid frequency, which exhibit a high degree of correlation in time. Both types of waves show simultaneous large amplitude variations of the order of 30-40 dB on time scales of a few hundreds of ms. Possible interpretations which may account for the observed correlation are investigated. Arguments are given which suggest that such events could be the signature of small scale non-linear structures in the plasma.