  In the events of the type $e^+e^- \rightarrow W^+W^- \rightarrow$ 4 jets,
$e^+e^- \rightarrow t\bar{t} \rightarrow bW^+\bar{b}W^-$, particle production
could depend in a non-trivial way on the kinematics of the process. It is shown
that QCD interference effects are negligible for energetic perturbative
emission, but soft perturbative gluons and non-perturbative fragmentation could
induce colour correlations. Possible consequences for LEP 2 and NLC events are
briefly addressed.
