[en] Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb^-1. The measurements were made in the kinematic range Q²<1 GeV², 0.20< y<0.85 and x_P<0.025, where Q² is the photon virtuality, y is the inelasticity and x_P is the fraction of the proton momentum taken by the diffractive exchange. The two jets with the highest transverse energy, E^jet_T, were required to satisfy E^jet_T>7.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5<η^jet<1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton. (orig.)