  Medium-induced parton energy loss is widely considered to underly the
suppression of high-pt leading hadron spectra in 200 GeV/A Au+Au collisions at
RHIC. Its description implies a characteristic kt-broadening of the subleading
hadronic fragments associated to the hard parton. However, this latter effect
is more difficult to measure and remained elusive so far. Here, we discuss how
it affects genuine jet observables which are accessible at LHC and possibly at
RHIC. We find that the kt-broadening of jet multiplicity distributions provides
a very sensitive probe of the properties of dense QCD matter, whereas the
sensitivity of jet energy distributions is much weaker. In particular, the
sensitive kinematic range of jet multiplicity distributions is almost
unaffected by the high multiplicity background.
