  We have performed simultaneous X-ray and radio observations of thirteen
Galactic centre low-mass X-ray binaries in 1998 April using the Wide-Field
Cameras onboard BeppoSAX and the Australia Telescope Compact Array, the latter
simultaneously at 4.8 and 8.64 GHz. We detect two Z sources, GX 17+2 and GX
5-1, and the unusual `hybrid' source GX 13+1. Upper limits, which are
significantly deeper than previous non-detections, are placed on the radio
emission from two more Z sources and seven atoll sources. Hardness-Intensity
diagrams constructed from the Wide-Field Camera data reveal GX 17+2 and GX 5-1
to have been on the lower part of the horizontal branch and/or the upper part
of the normal branch, at the time of the observations, and the two non-detected
Z sources, GX 340+0 and GX 349+2, to have been on the lower part of the normal
branch. This is consistent with the previous empirically-determined relation
between radio and X-ray emission from Z sources, in which radio emission is
strongest on the Horizontal branch and weakest on the Flaring branch. For the
first time we have information on the X-ray state of atoll sources, which are
clearly radio-quiet relative to the Z sources, during periods of observed radio
upper limits. We place limits on the linear polarisation from the three
detected sources, and use accurate radio astrometry of GX 17+2 to confirm that
it is probably not associated with the optical star NP Ser. Additionally we
place strong upper limits on the radio emission from the X-ray binary 2S
0921-630, disagreeing with suggestions that it is a Z-source viewed edge-on.
