  We present the second paper of a series of publications aiming at obtaining a
better understanding regarding the nature of type Ia supernovae (SNIa)
progenitors by studying a large sample of detached F, G and K main sequence
stars in close orbits with white dwarf companions (i.e. WD+FGK binaries). We
employ the LAMOST (Large Sky Area Multi-Object Fibre Spectroscopic Telescope)
data release 4 spectroscopic data base together with GALEX (Galaxy Evolution
Explorer) ultraviolet fluxes to identify 1,549 WD+FGK binary candidates (1,057
of which are new), thus doubling the number of known sources. We measure the
radial velocities of 1,453 of these binaries from the available LAMOST spectra
and/or from spectra obtained by us at a wide variety of different telescopes
around the globe. The analysis of the radial velocity data allows us to
identify 24 systems displaying more than 3sigma radial velocity variation that
we classify as close binaries. We also discuss the fraction of close binaries
among WD+FGK systems, which we find to be ~10 per cent, and demonstrate that
high-resolution spectroscopy is required to efficiently identify
double-degenerate SNIa progenitor candidates.
