  We report the results of a systematic photometric survey of the peripheral
regions of a sample of fourteen globular clusters in the outer halo of the
Milky Way at distances d_GC>25 kpc from the Galactic centre. The survey is
aimed at searching for the remnants of the host satellite galaxies where these
clusters could originally have been formed before being accreted onto the
Galactic halo. The limiting surface brightness varies within our sample, but
reaches muV_lim=30-32 mag arcsec^-2. For only two globular clusters (NGC 7492
and Whiting 1; already suggested to be associated with the Sagittarius galaxy)
we detect extended stellar populations that cannot be associated with either
the clusters themselves or with the surrounding Galactic field population. We
show that the lack of substructures around globular clusters at these
Galactocentric distances is still compatible with the predictions of
cosmological simulations whereby in the outer halo the Galactic globular
cluster system is built up through hierarchical accretion at early epochs.
