We present the analysis of XMM-Newton observations of three X-ray weak quasars: PG 1001+054, PG 1535+547 and PG 2112+059. All objects are absorbed by ionized material showing high column densities, NH = 2.9 × 10 22 cm −2 to NH = 1.9 × 10 23 cm −2 , and ionization parameters, ξ = 147 erg cm s −1 to ξ = 542 erg cm s −1 . The spectra of PG 1535+547 require an additional partial covering by neutral material with a column density of NH ≈ 9 × 10 22 cm −2 at a covering factor of ≈0.96. The spectra of PG 1535+547 show systematic residuals in the energy range from ∼ 4k eV to∼6 keV, which are inconsistent with Kα-fluorescence-emission of neutral or ionized iron under the assumption of a Gaussian line profile. They can be described with a relativistic disk line (Laor) and establish therefore the second X-ray weak quasar with such a spectral characteristic. Our results together with the findings of Brinkmann et al. (2004, A&A, 414, 107) and Piconcelli et al. (2004a, MNRAS, 351, 161), indicate that warm absorbers characterized by high column densities and ionization parameters are typical of X-ray weak quasars. The occurrence of a variable relativistic broad Fe Kα fluorescence line in two out of the five well studied X-ray weak quasars might indicate a second general characteristic of the entire object class. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.