  We present results for the light quark masses obtained from a lattice QCD
simulation with N_f=2 degenerate Wilson dynamical quark flavours. The sea quark
masses of our lattice, of spacing a ~ 0.06 fm, are relatively heavy, i.e., they
cover the range corresponding to 0.60 <~ M_P/M_V <~ 0.75. After implementing
the non-perturbative RI-MOM method to renormalise quark masses, we obtain
m_{ud}^{MS}(2 GeV)=4.3 +- 0.4^{+1.1}_{-0} MeV, and m_s^{MS}(2 GeV)=101 +-
8^{+25}_{-0} MeV, which are about 15% larger than they would be if renormalised
perturbatively. In addition, we show that the above results are compatible with
those obtained in a quenched simulation with a similar lattice.
