Multiply charged ion production in He, Ne, Ar and Xe has been investigated using a 1 ps Nd-glass laser pulse at lambda = 1053 nm with intensities in the 10(13)-10(18) W cm-2 range. All the outer-shell electrons are removed except in Ne gas in which ion charge states up to Ne7+ are observed. The influence of the polarization of the laser radiation is also investigated. Experimental ion production rates are compared with those predicted by tunnelling and barrier-suppression ionization models.