  A fraction of galaxy clusters host diffuse radio sources called radio halos,
radio relics and mini-halos. We present the sample and first results from the
Extended GMRT Radio Halo Survey (EGRHS)- an extension of the GMRT Radio Halo
Survey (GRHS, Venturi et al. 2007, 2008). It is a systematic radio survey of
galaxy clusters selected from the REFLEX and eBCS X-ray catalogs . Analysis of
GMRT data at 610/ 235/ 325 MHz on 12 galaxy clusters are presented. We report
the detection of a newly discovered mini-halo in the cluster RXJ1532.9+3021 at
610 MHz. A small scale relic (~200 kpc) is suspected in the cluster Z348. We do
not detect cluster-scale diffuse emission in 11 clusters. Robust upper limits
on the detection of radio halo of size of 1 Mpc are determined. We also present
upper limits on the detections of mini-halos in a sub-sample of cool-core
clusters. The upper limits for radio halos and mini-halos are plotted in the
radio power- X-ray luminosity plane and the correlations are discussed. Diffuse
extended emission, not related to the target clusters, but detected as
by-products in the sensitive images of two of the cluster fields (A689 and
RXJ0439.0+0715) are reported. Based on the information about the presence of
radio halos (or upper limits), available on 48 clusters out of the total sample
of 67 clusters (EGRHS+GRHS), we find that ~23% of the clusters host radio
halos. The radio halo fraction rises to ~31%, when only the clusters with X-ray
luminosities >8x10^44 erg/s are considered. Mini-halos are found in ~50 % of
cool-core clusters. A qualitative examination of the X-ray images of the
clusters with no diffuse radio emission indicates that a majority of these
clusters do not show extreme dynamical disturbances and supports the idea that
mergers play an important role in the generation of radio halos/relics.
