  Monte-Carlo simulations of abelian projection of $T \neq 0$ pure lattice QCD
show that 1) Polyakov loops written in terms of abelian link fields alone play
a role of an order parameter of deconfinement transition, 2) the abelian
Polyakov loops are decomposed into contributions from Dirac strings of
monopoles and from photons, 3) vanishing of the abelian Polyakov loops in the
confinement phase is due to the Dirac strings alone and the photons give a
finite contribution in both phases. Moreover, these results appear to hold good
with any abelian projection as seen from the studies in the maximally abelian
gauge and in various unitary gauges.
