The NA60 experiment has studied low-mass muon pair production in proton-nucleus collisions with a system of Be, Cu, In, W, Pb and U targets, using a 400 GeV proton beam at the CERN SPS. The transverse momentum spectra of the ρ/ω and φ mesons are measured in the full p T range accessible, from p T = 0 up to 2 GeV/c. The nuclear dependence of the production cross sections of the η, ω and φ mesons has been found to be consistent with the power law σ pA ∝ A α , with the α parameter increasing as a function of p T for all the particles, and an approximate hierarchy α η ≈ α φ > α ω . The cross section ratios σ η /σ ω , σ ρ /σ ω and σ φ /σ ω have been studied as a function of the size A of the production target, and an increase of the η and φ yields relative to the ω is observed from p-Be to p-U collisions. a