  We present the results of a 9.3 square degree infrared (ZYJHK) survey in the
Upper Scorpius association extracted from the UKIRT Infrared Deep Sky Survey
(UKIDSS) Galactic Cluster Survey Early Data Release. We have selected a total
of 112 candidates from the ($Z-J$,$Z$) colour-magnitude diagram over the
Z=12.5-20.5 magnitude range, corresponding to M = 0.25-0.01 Msun at an age of 5
Myr and a distance of 145 pc. Additional photometry in J and K filters revealed
most of them as reddened stars, leaving 32 possible members. Among them, 15
have proper motion consistent with higher mass members from Hipparcos and
optical spectra with strong Halpha in emission and weak gravity features. We
have also extracted two lower mass candidate members for which no optical
spectra are in hand. Three members exhibit strong Halpha equivalent widths (>20
Angstroms), suggesting that they could still undergo accretion whereas two
other dwarfs show signs of chromospheric activity. The likelihood of the
binarity of a couple of new stellar and substellar members is discussed as
well.
