  The critical curve of string tension as a function of the temperature is
computed in SU(3) Lattice QCD. We present the results for the string tension
utilizing a pair of Polyakov loop and antiloop, with two different techniques.
We compare the colour averaged loop-antiloop which is gauge invariant but is
only adequate to study the string tension, and the colour singlet loop-antiloop
using the Landau gauge fixing which also enables to compute the coulomb part of
the free energy.
