We study by numerical simulations on a lattice the behavior of the gauge-invariant two-point correlation functions of the gauge-field strengths across the deconfinement phase transition, both for the pure-gauge SU(3) theory and for full QCD with two flavors. Quenched data agree within errors with previous determinations, but have much higher statistics. A best-fit analysis of the data has been performed, both for the quenched and the full-QCD case, showing that the electric gluon condensate drops to zero at the deconfining phase transition