  The HI distribution at the epoch of reionization (EOR) is largely determined
by the sizes and distribution of the ionized regions. In the scenario where the
ionized regions have comoving sizes of the order of a few Mpc, the large scale
statistical properties of the HI distribution are dominated by the Poisson
noise of the discrete ionized regions, and it is highly non-Gaussian. We
investigate the possibility of probing reionization by studying these
non-Gaussian features using future radio interferometric observations of
redshifted 21 cm HI radiation. We develop a formalism relating correlations
between the visibilities measured at three different baselines and frequencies
to the bispectrum of HI fluctuations. For visibilities at the same frequency,
this signal is found to be of the same order as the two visibility correlation
which probes the HI power spectrum. For visibilities at different frequencies,
we find that the correlations decay within a frequency difference of ~1 MHz.
This implies that it is, in principle, straightforward to extract this HI
signal from various contaminants which are believed to have a continuum spectra
and are expected to be correlated even at large frequency separations.
