  Jet flavour identification in multi-TeV e+e- collisions is expected to
provide insights on new phenomena at scales beyond those probed by the LHC. The
anticipated high track density and jet collimation represent a new challenge to
jet tagging algorithms. A method, based on the sampling of the jet charged
multiplicity, sensitive to the long decay length and large decay multiplicity
of heavy flavour hadrons is proposed and the expected performances for the
tagging of e+e- -> bb events at 3 TeV are discussed.
