We study the electromagnetic (e.m.) conductivity of QGP in a magnetic background by lattice simulations with $N_f = 2+1$ dynamical rooted staggered fermions at the physical point. We study the correlation functions of the e.m.~currents at $T=200,,250
$,MeV and use the Tikhonov approach to extract the conductivity. This is found to rise with the magnetic field in the direction parallel to it and to decrease in the transverse direction, giving evidence for both the Chiral Magnetic Effect and the magnetoresistance phenomenon in QGP. We also estimate the chiral charge relaxation time in QGP.
