We have tried to determine the flux of the ultraviolet background radiation
field from the column density ratios of various ions in several absorption
systems observed in the spectra of QSOs. We find that in most cases the fl
ux is considerably higher than what has been estimated to be contributed by
the AGNs. The excess flux could originate locally in hot stars. In a few c
ases we have been able to show that such galactic flux can only contribute
a part of the total required flux. The results suggest that the background
gets a significant contribution from an unseen QSO population.