We present a study of 40 low-latitude unidentified 3EG gamma-ray sources which were found to be not positionally coincident with any known class of potential gamma-ray emitters in the Galaxy ( Romero , Benaglia & Torres , 1999 ) .
We have performed a variability analysis which reveals that many of these 40 sources are variable .
These sources have , in addition , a steep mean value of the gamma-ray spectral index , < \Gamma > = 2.41 \pm 0.2 , which , combined with the high level of variability , seems to rule out a pulsar origin .
The positional coincidences with uncatalogued candidates to supernova remnants were also studied .
Only 7 sources in the sample are spatially coincident with these candidates , a result that is shown to be consistent with the expected level of pure chance association .
A complementary search for weak radio counterparts was also conducted and the results are presented as an extensive table containing all significant point-like radio sources within the 40 EGRET fields .
We argue that in order to produce the high variability , steep gamma-ray spectra , and absence of strong radio counterparts observed in some of the gamma-ray sources of our sample , a new class of objects should be postulated , and we analyze a viable candidate .