  Assuming the weak energy condition, we study the nature of the non-central
shell-focussing singularity which can form in the gravitational collapse of a
spherical compact object in classical general relativity. We show that if the
radial pressure is positive, the singularity is covered by a horizon. For
negative radial pressures, the singularity will be covered if the ratio of
pressure to the density is greater than -1/3 and naked if this ratio is $\leq
-1/3$.
