  Interference of single-photon wave packets at a beam splitter usually leads
to an anticorrelation of the light intensity in the two output ports of the
beam splitter. The effect may be regarded as ``bunching'' of the photons at the
beam splitter and has widely been interpreted as a result of quantum mechanical
interference between the probability amplitudes of indistinguishable bosonic
particles. Here we show that when the wave packets are sufficiently distorted,
then the opposite behaviour is observed, i.e., simultaneous clicks of the
photodetectors in the two output ports are favoured, which may be regarded as
``antibunching'' of the photons at the beam splitter.
