Low-metallicity star formation poses a central problem of cosmology , as it determines the characteristic mass scale and distribution for the first and second generations of stars forming in our Universe . Here , we present a comprehensive investigation assessing the relative impact of metals and magnetic fields , which may both be present during low-metallicity star formation . We show that the presence of magnetic fields generated via the small-scale dynamo stabilises the protostellar disc and provides some degree of support against fragmentation . In the absence of magnetic fields , the fragmentation timescale in our model decreases by a factor of \sim 10 at the transition from Z = 0 to Z > 0 , with subsequently only a weak dependence on metallicity . Similarly , the accretion timescale of the cluster is set by the large-scale dynamics rather than the local thermodynamics . In the presence of magnetic fields , the primordial disc can become completely stable , therefore forming only one central fragment . At Z > 0 , the number of fragments is somewhat reduced in the presence of magnetic fields , though the shape of the mass spectrum is not strongly affected in the limits of the statistical uncertainties . The fragmentation timescale , however , increases by roughly a factor of 3 in the presence of magnetic fields . Indeed , our results indicate comparable fragmentation timescales in primordial runs without magnetic fields and Z > 0 runs with magnetic fields .