  We present radio observations of the black hole X-ray transient XTE
J1720-318, which was discovered in 2003 January as it entered an outburst. We
analyse the radio data in the context of the X-ray outburst and the broad-band
spectrum. An unresolved radio source was detected during the rising phase,
reaching a peak of nearly 5 mJy approximately coincident with the peak of the
X-ray lightcurve. Study of the spectral indices suggests that at least two
ejection events took place, the radio-emitting material expanding and becoming
optically thin as it faded. The broad-band spectra suggested that the accretion
disc dominated the emission, as expected for a source in the high/soft state.
The radio emission decayed to below the sensitivity of the telescopes for ~6
weeks but switched on again during the transition of the X-ray source to the
low/hard state. At least one ``glitch'' was superimposed on the otherwise
exponential decay of the X-ray lightcurve, which was reminiscent of the
multiple jet ejections of XTE J1859+226. We also present a K_s-band image of
XTE J1720-318 and its surrounding field taken with the VLT.
